Adhesive film for metal terminal and method for producing same, metal terminal equipped with adhesive film for metal terminal, exterior material for electric storage device, kit comprising exterior material for electric storage device and adhesive film for metal terminal, and electric storage device and

Abstract

An adhesive film for a metal terminal, which is present 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 comprising at least a polypropylene layer, the thickness of the polypropylene layer being greater than the thickness of the polypropylene layer in a direction parallel to the TD and in a cross section in the thickness direction, and the thickness of the polypropylene layer being greater than the thickness of the polypropylene layer in a direction parallel to the TD. A sea-island structure is observed in a cross-sectional image obtained using a scanning electron microscope, and the island ratio of the sea-island structure in the polypropylene layer is 20% or less.

Description

Technical Field

[0001] The present invention relates to an adhesive film for metal terminals, a method for manufacturing the same, a metal terminal with an adhesive film for metal terminals, an exterior material for electrical storage devices, a kit including the exterior material for electrical storage devices and the adhesive film for metal terminals, and an electrical storage device and a method for manufacturing the same. Background Art

[0002] Currently, various types of electrical storage devices have been developed. However, in all electrical storage devices, an exterior material for electrical storage devices has become an indispensable component for encapsulating electrical storage device elements such as electrodes and electrolytes. Conventionally, as the exterior material for electrical storage devices, a metal exterior material for electrical storage devices has been mostly used. However, in recent years, with the high-performance development of electric vehicles, hybrid electric vehicles, computers, cameras, mobile phones, etc., various shapes have been required for electrical storage devices, and at the same time, thinning and lightening have also been required. However, in the case of the currently mostly used metal exterior material for electrical storage devices, there are disadvantages that it is difficult to follow the diversification of shapes, and there is also a limit in terms of lightening.

[0003] Therefore, in recent years, as an exterior material for electrical storage devices that can be easily processed into various shapes and can achieve thinning and lightening, a laminated sheet in which a base material layer / an adhesive layer / a barrier layer / a heat-sealable resin layer are laminated in this order has been proposed. In the case of using such a laminated film-like exterior material for electrical storage devices, by heat-sealing the peripheral portion of the exterior material for electrical storage devices in a state where the heat-sealable resin layers located on the innermost layer of the exterior material for electrical storage devices face each other, the electrical storage device elements are encapsulated with the exterior material for electrical storage devices.

[0004] The metal terminal protrudes from the heat-sealed portion of the exterior material for electrical storage devices, and the electrical storage device elements encapsulated by the exterior material for electrical storage devices are electrically connected to the outside through the metal terminals that are electrically connected to the electrodes of the electrical storage device elements. That is, in the heat-sealed portion of the exterior material for electrical storage devices, the portion where the metal terminal is located is heat-sealed in a state where the metal terminal is clamped by the heat-sealable resin layer. Since the metal terminal and the heat-sealable resin layer are made of materials with different types, the adhesion at the interface between the metal terminal and the heat-sealable resin layer is likely to decrease.

[0005] Therefore, an adhesive film is sometimes disposed between the metal terminal and the heat-sealable resin layer for the purpose of improving their adhesion and the like. As such an adhesive film, for example, the film described in Patent Document 1 can be cited.

[0006] Prior Art Documents

[0007] Patent Documents

[0008] Patent Document 1: Japanese Unexamined Patent Application Publication No. 2015-79638 Summary of the Invention

[0009] Technical Problem to be Solved by the Invention

[0010] In recent years, with the high-capacity of electrical storage devices, the thickness of the adhesive film disposed between the metal terminal and the exterior material of the electrical storage device has a tendency to increase. As the thickness of the adhesive film becomes larger, the amount of moisture (water vapor) entering the electrical storage device through the adhesive film also tends to increase. Once a large amount of moisture enters the electrical storage device, various problems such as deterioration of the electrical storage device elements will occur.

[0011] The main object of the present invention is to provide an adhesive film for a metal terminal, which is disposed between the metal terminal electrically connected to the electrode of the electrical storage device element and the exterior material of the electrical storage device for encapsulating the electrical storage device element, and can suppress water vapor from permeating into the electrical storage device through the adhesive film for the metal terminal when the adhesive film for the metal terminal is disposed between the metal terminal and the exterior material of the electrical storage device. In addition, the object of the present invention is also to provide a method for manufacturing the adhesive film for the metal terminal, a metal terminal with the adhesive film for the metal terminal, an exterior material for the electrical storage device, a kit including the exterior material for the electrical storage device and the adhesive film for the metal terminal, an electrical storage device, and a method for manufacturing the electrical storage device.

[0012] Technical Solution for Solving the Technical Problem

[0013] The inventors of the present invention conducted in-depth research to solve the above technical problems. As a result, it was found that in the following adhesive film for a metal terminal, when the adhesive film for the metal terminal is disposed between the metal terminal and the exterior material of the electrical storage device, water vapor can be suppressed from permeating into the electrical storage device through the adhesive film for the metal terminal. The adhesive film for the metal terminal is disposed between the metal terminal electrically connected to the electrode of the electrical storage device element and the exterior material of the electrical storage device for encapsulating the electrical storage device element. The adhesive film for the metal terminal at least includes a polypropylene layer, and an island structure is observed in the cross-sectional image obtained by a scanning electron microscope in the direction parallel to TD and the thickness direction of the polypropylene layer, and the island ratio of the island structure of the polypropylene layer is 20% or less. The present invention was completed based on this discovery through further repeated research.

[0014] That is, the present invention provides an invention in the following manner.

[0015] An adhesive film for a metal terminal, which is disposed between the metal terminal electrically connected to the electrode of the electrical storage device element and the exterior material of the electrical storage device for encapsulating the electrical storage device element,

[0016] The above-mentioned adhesive film for a metal terminal at least includes a polypropylene layer,

[0017] In the cross-sectional image in the thickness direction of the polypropylene layer in the direction parallel to TD obtained using a scanning electron microscope, a sea-island structure was observed.

[0018] The island ratio of the above-mentioned sea-island structure of the above-mentioned polypropylene layer is 20% or less.

[0019] Advantages of the Invention

[0020] According to the present invention, it is possible to provide an adhesive film for a metal terminal, which is present between a metal terminal electrically connected to an electrode of an electrical storage device element and an exterior material for an electrical storage device that encapsulates the electrical storage device element. When the adhesive film for a metal terminal is disposed between the metal terminal and the exterior material for an electrical storage device, it is possible to suppress water vapor from permeating through the adhesive film for a metal terminal into the interior of the electrical storage device. In addition, an object of the present invention is to provide a method for manufacturing the adhesive film for a metal terminal, a metal terminal with the adhesive film for a metal terminal, an exterior material for an electrical storage device, a kit including the exterior material for an electrical storage device and the adhesive film for a metal terminal, and an electrical storage device and a method for manufacturing the same. BRIEF DESCRIPTION OF THE DRAWINGS

[0021] Figure 1 is a plan view of a schematic diagram of an electrical storage device of the present invention.

[0022] Figure 2 is Figure 1 a cross-sectional view of a schematic diagram of line A - A' of

[0023] Figure 3 is Figure 1 a cross-sectional view of a schematic diagram of line B - B' of

[0024] Figure 4 is a cross-sectional view of a schematic diagram of the adhesive film for a metal terminal of the present invention.

[0025] Figure 5 is a cross-sectional view of a schematic diagram of the adhesive film for a metal terminal of the present invention.

[0026] Figure 6 is a cross-sectional view of a schematic diagram of the adhesive film for a metal terminal of the present invention.

[0027] Figure 7 is a cross-sectional view of a schematic diagram of the adhesive film for a metal terminal of the present invention.

[0028] Figure 8 is a cross-sectional view of a schematic diagram of the exterior material for an electrical storage device of the present invention.

[0029] Figure 9 is a schematic diagram for explaining a method for measuring the water vapor transmission rate of the adhesive film for a metal terminal of the present invention.

[0030] Figure 10 It is a schematic diagram for explaining a method for measuring the adhesion strength between an adhesive film and an exterior material.

[0031] Figure 11 It is a schematic diagram for explaining a method for measuring the adhesion strength between an adhesive film and an exterior material.

[0032] Figure 12 It is a schematic diagram for explaining a method for measuring the adhesion strength between an adhesive film and an exterior material.

[0033] Figure 13 It is a schematic diagram for explaining a method for measuring the adhesion strength between an adhesive film and an exterior material. Detailed implementation mode

[0034] The adhesive film for metal terminals of the present invention is an adhesive film for metal terminals existing between a metal terminal electrically connected to an electrode of an electrical storage device element and an exterior material for an electrical storage device encapsulating the electrical storage device element. The adhesive film for metal terminals is characterized in that it at least includes a polypropylene layer, and in a cross-sectional image obtained by a scanning electron microscope of a cross-section in the direction parallel to TD and the thickness direction of the polypropylene layer, a sea-island structure is observed, and the island portion ratio of the sea-island structure of the polypropylene layer is 20% or less.

[0035] Since the adhesive film for metal terminals of the present invention has such characteristics, when the adhesive film for metal terminals is disposed between the metal terminal and the exterior material for an electrical storage device, water vapor can be inhibited from permeating into the electrical storage device through the adhesive film for metal terminals.

[0036] In addition, the electrical storage device of the present invention is characterized in that it includes: an electrical storage device element having at least a positive electrode, a negative electrode, and an electrolyte; an exterior material for an electrical storage device encapsulating the electrical storage device element; and metal terminals respectively electrically connected to the positive electrode and the negative electrode and protruding to the outside of the exterior material for an electrical storage device, and between the metal terminal and the exterior material for an electrical storage device, there is the adhesive film for metal terminals of the present invention.

[0037] Hereinafter, the adhesive film for metal terminals of the present invention, its manufacturing method, the electrical storage device, and its manufacturing method will be described in detail.

[0038] In addition, in this specification, regarding a numerical range, the numerical range indicated by "~" means "above" and "below". For example, the expression "2~15 mm" means 2 mm or more and 15 mm or less. In the numerical ranges described stepwise in the present invention, the upper limit value or the lower limit value described in a certain numerical range can be replaced with the upper limit value or the lower limit value of another numerically described stepwise range. In addition, the upper limit values described individually can be combined with each other, the upper limit value and the lower limit value, or the lower limit values and the lower limit values as numerical ranges, respectively. In addition, in the numerical ranges described in the present invention, the upper limit value or the lower limit value described in a certain numerical range can be replaced with the value shown in the examples.

[0039] In addition, as a method for confirming the MD of the adhesive film for metal terminals, there is a method of observing the cross section of the adhesive film for metal terminals with an electron microscope to confirm the sea-island structure. In this method, the direction parallel to the cross section having the largest average diameter of the shape of the islands in the direction perpendicular to the thickness direction of the adhesive film for metal terminals can be determined as the MD. Specifically, for the cross section in the length direction of the adhesive film for metal terminals and each cross section (a total of 10 cross sections) from the direction parallel to the cross section in the length direction to the direction perpendicular to the cross section in the length direction with the angle changed by 10 degrees each time, the sea-island structure is confirmed by observing with electron microscope photographs. Then, in each cross section, the shape of each island is observed. Regarding the shape of each island, the straight-line distance connecting the leftmost end and the rightmost end in the direction perpendicular to the thickness direction of the adhesive film for metal terminals is defined as the diameter y. Calculate the average of the top 20 diameters y in descending order of the diameter y of the shape of the islands in each cross section. The direction parallel to the cross section having the largest average of the diameter y of the shape of the islands is determined as the MD. In addition, for example, the adhesive film for metal terminals can be placed in an environment of 150°C for 2 minutes and then the heat shrinkage rate is measured, and the one with the larger shrinkage rate is determined as the MD.

[0040] 1. Adhesive Film for Metal Terminals

[0041] The adhesive film for metal terminals of the present invention is present between the metal terminal electrically connected to the electrode of the electrical storage device element and the exterior material for electrical storage device that encapsulates the electrical storage device element. Specifically, for example, as Figures 1 to 3 shown, the adhesive film 1 for metal terminals of the present invention is present between the metal terminal 2 electrically connected to the electrode of the electrical storage device element 4 and the exterior material 3 for electrical storage device that encapsulates the electrical storage device element 4. In addition, the metal terminal 2 protrudes to the outside of the exterior material 3 for electrical storage device, and in the peripheral portion 3a of the heat-sealed exterior material 3 for electrical storage device, it is clamped by the exterior material 3 for electrical storage device with the adhesive film 1 for metal terminals interposed therebetween.

[0042] In addition, in the present invention, the preliminary bonding process of the adhesive film for metal terminal to the metal terminal is carried out under the conditions of, for example, a temperature of about 140 to 160° C., a pressure of about 0.01 to 1.0 MPa, a time of about 3 to 15 seconds, and a number of times of about 3 to 6 times, and the main bonding process is carried out under the conditions of, for example, a temperature of about 160 to 240° C., a pressure of about 0.01 to 1.0 MPa, a time of about 3 to 15 seconds, and a number of times of about 1 to 3 times. In addition, the heating temperature when heat-sealing the metal terminal with the adhesive film for metal terminal through the outer packaging material for the storage device is usually in the range of about 180 to 210° C., and the pressure is usually about 1.0 to 5.0 MPa, and the time is about 1 to 5 seconds and the number of times is about 1.

[0043] The adhesive film 1 for metal terminals of the present invention (hereinafter, sometimes simply referred to as "adhesive film") is provided to improve the closeness between the metal terminal 2 and the outer packaging material 3 for the storage device. By improving the closeness between the metal terminal 2 and the outer packaging material 3 for the storage device, the sealing of the storage device element 4 is improved. As described above, when the storage device element 4 is heat-sealed, the metal terminal 2 electrically connected to the electrode of the storage device element 4 is made to protrude to the outside of the outer packaging material 3 for the storage device to encapsulate the storage device element. At this time, the metal terminal 2 formed of metal and the heat-fusible resin layer 35 (a layer formed of a heat-fusible resin such as polyolefin) located in the innermost layer of the outer packaging material 3 for the storage device are formed of different materials. Therefore, when such an adhesive film is not used, the sealing of the storage device element is easily reduced at the interface between the metal terminal 2 and the heat-fusible resin layer 35.

[0044] [Polypropylene layer 11]

[0045] The adhesive film 1 for metal terminals of the present invention has a polypropylene layer having an island portion ratio of less than 20% of the island structure described later. In the present invention, the polypropylene layer having an island portion ratio of less than 20% of the island structure described later is referred to as "polypropylene layer 11". As described later, in the case where the adhesive film 1 for metal terminals of the present invention is multilayered, the adhesive film 1 for metal terminals may include, in addition to the polypropylene layer 11, a polypropylene layer having an island portion ratio of more than 20% of the island structure. For example, the first layer 12a, the second layer 12b, the third layer 12c, the fourth layer 12d, the substrate, etc. described later may be a polypropylene layer having an island portion ratio of more than 20% of the island structure.

[0046] In the polypropylene layer 11, the island part of the sea-island structure is a region mainly composed of ethylene (for example, the ethylene content is 80% by mass or more, 90% by mass or more, 95% by mass or more, 99% by mass or more, etc.), and the sea part of the sea-island structure is a region composed mainly of polypropylene (for example, the propylene content is 80% by mass or more, 90% by mass or more, 95% by mass or more, 99% by mass or more, etc.).

[0047] The adhesive film 1 for metal terminals of the present invention includes at least one polypropylene layer 11. The adhesive film 1 for metal terminals can be a single layer or a multi-layer. The adhesive film 1 for metal terminals is preferably composed of a single layer of the polypropylene layer 11, for example. Figure 4 A diagram showing that the adhesive film 1 for metal terminals is composed of a single layer of the polypropylene layer 11.

[0048] In addition, when the adhesive film 1 for metal terminals is composed of multiple layers, the polypropylene layer 11 is preferably not a layer that constitutes the surface of the adhesive film 1 for metal terminals. When the adhesive film 1 for metal terminals is multi-layered, the adhesive film 1 for metal terminals preferably has a laminated structure of 3 to 6 layers, and the polypropylene layer 11 is preferably not a layer that constitutes the surface of the adhesive film 1 for metal terminals. Figure 5 A diagram showing a laminated structure of the adhesive film 1 for metal terminals having a three-layer structure in which the first layer 12a on the side of the outer packaging material 3 for electrical storage devices, the polypropylene layer 11, and the second layer 12b on the side of the metal terminal 2 are laminated in sequence. In addition, Figure 6 A diagram showing a laminated structure of the adhesive film 1 for metal terminals having a four-layer structure in which the first layer 12a on the side of the outer packaging material 3 for electrical storage devices, the polypropylene layer 11, the third layer 12c, and the second layer 12b on the side of the metal terminal 2 are laminated in sequence. In addition, Figure 7 As described later, a diagram showing a laminated structure in which an adhesion promoter layer 13 is provided between these layers for the purpose of firmly bonding the polypropylene layer 11 and the first layer 12a, and the polypropylene layer 11 and the second layer 12b, respectively.

[0049] From the viewpoint of more suitably exerting the effects of the present invention, the ratio of the thickness of the polypropylene layer 11 to the thickness of the adhesive film 1 for metal terminals is preferably about 0.20 or more, more preferably about 0.25 or more, and further preferably about 0.30 or more. In addition, it is preferably about 0.90 or less, more preferably about 0.85 or less, and further preferably about 0.80 or less. As a preferred range, 0.20 to 0.90 or so, 0.20 to 0.85 or so, 0.20 to 0.80 or so, 0.25 to 0.90 or so, 0.25 to 0.85 or so, 0.25 to 0.80 or so, 0.30 to 0.90 or so, 0.30 to 0.85 or so, 0.30 to 0.80 or so can be cited.

[0050] The polypropylene layer 11 is a layer formed of polypropylene. Examples of the polypropylene include crystalline or amorphous polypropylenes such as homopolypropylene, block copolymers of polypropylene (e.g., block copolymers of propylene and ethylene), random copolymers of polypropylene (e.g., random copolymers of propylene and ethylene); and terpolymers of ethylene-butene-propylene. Among these polypropylenes, homopolypropylene and block copolymers of polypropylene are also preferred. In addition, even in the case of homopolypropylene, polymers composed only of propylene are usually rare, and usually, they are copolymerized with ethylene. In the present invention, homopolypropylene with a particularly small proportion of ethylene (i.e., polypropylene with an island portion ratio of 20% or less in the above-mentioned sea-island structure) is preferably used.

[0051] In addition, the polypropylene of the polypropylene layer 11 may contain modified polypropylene or may be modified polypropylene. Examples of the modified polypropylene include acid-modified polypropylene. The acid-modified polypropylene is not particularly limited as long as it is polypropylene modified with an acid, and preferably includes polypropylene graft-modified with an unsaturated carboxylic acid or its acid anhydride. Specific examples of the polypropylene that can be acid-modified include crystalline or amorphous polypropylenes such as homopolypropylene, block copolymers of polypropylene (e.g., block copolymers of propylene and ethylene), random copolymers of polypropylene (e.g., random copolymers of propylene and ethylene); and terpolymers of ethylene-butene-propylene. Among these polypropylenes, homopolypropylene and block copolymers of polypropylene are preferred.

[0052] Examples of the carboxylic acid or its acid anhydride used for acid modification include maleic acid, acrylic acid, itaconic acid, crotonic acid, maleic anhydride, itaconic anhydride, etc. The resin layer containing maleic anhydride preferably shows a peak derived from maleic anhydride when analyzed by infrared spectroscopy. For example, if maleic anhydride-modified polyolefin is measured by infrared spectroscopy, peaks derived from maleic anhydride can be detected at around a wave number of 1760 cm -1 and around a wave number of 1780 cm -1 If the polypropylene layer 11 is a layer composed of maleic anhydride-modified polypropylene, peaks derived from maleic anhydride can be detected when measured by infrared spectroscopy. However, if the degree of acid modification is low, the peaks are small and sometimes undetectable. In such a case, nuclear magnetic resonance spectroscopy can be used for analysis.

[0053] The polypropylene layer 11 may be formed of a single resin component alone or a blend polymer obtained by combining two or more resin components.

[0054] In the present invention, as long as the island portion ratio of the sea-island structure of the polypropylene layer 11 is 20% or less, from the viewpoint of more suitably exerting the effects of the present invention, the island portion ratio is preferably about 18% or less, more preferably about 15% or less, further preferably about 10% or less, further preferably about 5% or less, further preferably less than about 5%, further preferably about 3% or less, further preferably about 1% or less, etc. In addition, it is preferably about 0% or more, about 0.02% or more, about 0.04% or more, etc. As the preferred range, 0 to about 20%, 0 to about 18%, 0 to about 15%, 0 to about 10%, 0 to about 5%, more than 0% and less than about 5%, 0 to about 3%, 0 to about 1%, 0.02 to about 20%, 0.02 to about 18%, 0.02 to about 15%, 0.02 to about 10%, 0.02 to about 5%, more than 0.02% and less than about 5%, 0.02 to about 3%, 0.02 to about 1%, 0.04 to about 20%, 0.04 to about 18%, 0.04 to about 15%, 0.04 to about 10%, 0.04 to about 5%, more than 0.04% and less than about 5%, 0.04 to about 3%, 0.04 to about 1% can be cited. The island portion ratio of the sea-island structure of the polypropylene layer 11 can be adjusted, for example, by controlling the content of polyethylene in the polypropylene film, the polymerization form (homopolymerization, block or random), and the film-forming conditions (temperature and speed during film formation, cooling temperature and speed, etc.). The island portion ratio of the sea-island structure of the polypropylene layer is a value measured by the following method.

[0055] <Measurement of the island portion ratio of the sea-island structure of the polypropylene layer>

[0056] Embed the adhesive film in a thermosetting epoxy resin and cure it. Use a commercially available rotary microtome and a diamond knife to make a cross-section in the target direction (a cross-section parallel to the TD and in the thickness direction). At this time, use a cryo-ultramicrotome using liquid nitrogen to make the cross-section at -70°C. After staining each embedding resin with ruthenium tetroxide for 12 hours, trim the swollen part with a microtome, and cut in the direction of the MD from 100 nm in increments of 300 nm. When cutting a total of about 1 μm to 2 μm, observe the cross-section where the polypropylene layer is exposed as follows. For the stained cross-section, observe it using a field emission scanning electron microscope (measurement conditions: 3 kV 20 mA High WD6 mm detector (Upper)) to obtain an image (magnification: 10,000 times). Then, use image processing software capable of binarizing the image to binarize the island part and the sea part of the sea-island structure in the image, and calculate the ratio of the total area of the island part (total area of the island part / area of the measurement range of the image).

[0057] [Image processing conditions]

[0058] Image processing was performed using the image analysis software ImageJ. Specifically, SEM images were obtained in the form of digital files of grayscale images (JPEG), and processed according to the following binarization processing procedures and parameters. Pixels with a tone (bright) above the threshold were output as 1, and pixels with a tone (dark) less than the threshold were output as 0, which were respectively defined as island parts and sea parts.

[0059] <Binarization Processing>

[0060] 1. Removal of spike noise (Despeckle)

[0061] 2. Removal of the outline of the island part (Remove Outliers radius = 4 threshold = 1 which = Bright)

[0062] 3. Removal of the outline of the sea part (Remove Outliers radius = 4 threshold = 1 which = Dark)

[0063] 4. Removal of spike noise (Despeckle)

[0064] 5. Gaussian blur in the X-axis (short side of the sample) direction (threshold = 3 pixels)

[0065] 6. Contrast enhancement (saturated = 0.2)

[0066] 7. Removal of the outline of the island part (Remove Outliers radius = 4 threshold = 1 which = Bright)

[0067] 8. Removal of the outline of the sea part (Remove Outliers radius = 4 threshold = 1 which = Dark)

[0068] 9. Otsu binarization

[0069] From the viewpoint of more suitably exerting the effects of the present invention, regarding the adhesive film 1 for metal terminals, after heating the adhesive film 1 for metal terminals under the conditions of a temperature of 200°C, a surface pressure of 0.25 MPa, and 16 seconds, in an environment of a temperature of 40°C, the ratio of the soft segment component measured by the solid echo method of pulsed NMR is preferably about 20% or less, more preferably about 18% or less, and further preferably about 16% or less. In addition, it is preferably about 3% or more, more preferably about 8% or more, and further preferably about 10% or more. As the preferred range, about 3 to 20%, about 3 to 18%, about 3 to 16%, about 8 to 20%, about 8 to 18%, about 8 to 16%, about 10 to 20%, about 10 to 18%, and about 10 to 16% can be cited. The ratio of the soft segment component of the adhesive film 1 after heating can be adjusted, for example, by controlling the content of polyethylene in the polypropylene film, the polymerization form (homopolymerization, block, or random), and the film-forming conditions (temperature and speed during film formation, cooling temperature and speed, etc.). The method for measuring the ratio of the soft segment component of the adhesive film for metal terminals after heating is as described below.

[0070] <Measurement of the ratio of the soft segment component of the adhesive film after heating>

[0071] Heat the adhesive film under the conditions of a temperature of 200°C, a surface pressure of 0.25 MPa, and 16 seconds as a sample. This heat treatment assumes the physical properties of the adhesive film after being configured between the exterior material for the electrical storage device and the metal terminal and being heat-sealed. Introduce the sample into a glass sample tube with a diameter of 10 mm, set the sample tube in a pulsed NMR device, hold it at 440°C for 5 minutes, and then obtain the free induction decay curve of the spin-spin relaxation of 1H by the solid echo method at 40°C. Set the number of scans in the solid echo method to 64 times. Separate the obtained decay curve waveform into three curves of three components originating from the hard segment component, the middle segment component, and the soft segment component. The waveform separation uses the analysis software "TD-NMRA (Version 4.3Rev 0.8)" manufactured by BRUKER Corporation. The hard segment component is obtained by fitting with a Gaussian function, and the middle segment component and the soft segment component are obtained by fitting with an exponential function. The measurement points up to 0.6 msec of the relaxation curve are used in the analysis. The fitting uses the following formula.

[0072] Y = A1×exp(-(t / τ1) w1 ) + A2×exp(-(t / τ2) w2 ) + A3×exp(-(t / τ3) w3 )

[0073] Among them, w1 to w3 are Weibull coefficients, with w1 taking a value of 2, and w2 and w3 taking a value of 1. A1 is the composition ratio of the hard segment component, A2 is the composition ratio of the middle segment component, A3 is the composition ratio of the soft segment component, τ1 represents the relaxation time of the hard segment component, τ2 represents the relaxation time of the middle segment component, τ3 represents the relaxation time of the soft segment component, and t is the time. The composition ratios A1, A2, and A3 are the average values measured at the same level 3 times.

[0074] In the polypropylene layer 11, known additives can be included as needed.

[0075] For example, in the polypropylene layer 11, a filler can be included as needed. By including a filler in the polypropylene layer 11, since the filler functions as a spacer, a short circuit between the metal terminal 2 and the barrier layer 33 of the exterior material 3 for the electrical storage device can be effectively suppressed. As the particle diameter of the filler, a range of about 0.1 to 35 μm, preferably about 5.0 to 30 μm, and more preferably about 10 to 25 μm can be cited. In addition, as the content of the filler, with respect to 100 parts by mass of the resin component forming the polypropylene layer 11, about 5 to 30 parts by mass, more preferably about 10 to 20 parts by mass can be cited respectively.

[0076] As the filler, any inorganic or organic filler can be used. As the inorganic filler, for example, carbon (charcoal, graphite), silica, alumina, barium titanate, iron oxide, silicon carbide, zirconia, zirconium silicate, magnesia, titanium oxide, calcium aluminate, calcium hydroxide, aluminum hydroxide, magnesium hydroxide, calcium carbonate, etc. can be cited. In addition, as the organic filler, for example, fluororesin, phenolic resin, urea resin, epoxy resin, acrylic resin, phenylmelamine-formaldehyde condensate, melamine-formaldehyde condensate, polymethyl methacrylate crosslinked product, polyethylene crosslinked product, etc. can be cited. From the viewpoints of shape stability, rigidity, and content resistance, alumina, silica, fluororesin, acrylic resin, and phenylmelamine-formaldehyde condensate are preferred, and among them, spherical alumina and silica are more preferred. As the mixing method of the filler mixed into the resin component forming the polypropylene layer 11, a method of melting and blending the two in advance with a Banbury mixer or the like and making the granulated product into a specified mixing ratio, a method of directly mixing with the resin component, etc. can be adopted.

[0077] In addition, in the polypropylene layer 11, colorants such as pigments can be included as needed. There is no particular limitation on the colorant, and colorants capable of coloring the resin layer can be suitably used. Specific examples of the colorant include pigments. As the pigment, various inorganic or organic pigments can be used. Specific examples of the pigment include, in addition to carbon (charcoal, graphite), silica, titanium oxide, iron oxide, zinc oxide, magnesium oxide, and calcium oxide exemplified in the above fillers, inorganic oxides such as titanium nitride, zirconium black oxide, copper oxide, cobalt oxide, and barium sulfate can also be preferably exemplified. In addition, organic pigments such as quinacridone pigments, polyazo pigments, and isoindolinone pigments can also be preferably exemplified. Carbon (charcoal, graphite) is usually a material used inside the electrical storage device, and there is no need to worry about elution into the electrolyte. In addition, an addition amount that provides a sufficient coloring effect without impairing the adhesiveness can be obtained, and it does not melt due to heat, and can increase the apparent melt viscosity of the added resin. In addition, it can prevent the pressure portion from thinning during thermal bonding (heat sealing), and can impart excellent sealing performance between the exterior material for the electrical storage device and the metal terminal.

[0078] The color of the polypropylene layer 11 is not particularly limited and can be selected according to the purpose. The polypropylene layer 11 is preferably black, gray, or white, for example.

[0079] When a pigment is added to the polypropylene layer 11, as the addition amount, for example, when using carbon black with a particle size of about 0.03 μm, about 0.05 to 0.3 parts by mass, preferably about 0.1 to 0.2 parts by mass, can be listed respectively with respect to 100 parts by mass of the resin component forming the polypropylene layer 11. By adding a pigment to the polypropylene layer 11, the presence or absence of the adhesive film 1 for the metal terminal can be detected by a sensor or can be visually inspected. In addition, when the above fillers and pigments are added to the polypropylene layer 11, the filler and the pigment can be added to the same polypropylene layer 11, but from the viewpoint of not interfering with the heat weldability of the adhesive film 1 for the metal terminal, the filler and the pigment are preferably added to multiple layers.

[0080] In the case where a pigment is added to the polypropylene layer 11, as the addition amount, for example, in the case of using carbon black having a particle size of about 0.03 μm, with respect to 100 parts by mass of the resin component forming the polypropylene layer 11, about 0.05 to 0.3 parts by mass, preferably about 0.1 to 0.2 parts by mass can be cited respectively. By adding a pigment to the polypropylene layer 11, the presence or absence of the adhesive film 1 for metal terminals can be detected by a sensor, or inspection can be carried out visually. Further, in the case where a filler and a pigment are added to the polypropylene layer 11, the filler and the pigment can be added in the same polypropylene layer 11, but from the viewpoint of not hindering the heat fusion property of the adhesive film 1 for metal terminals, the filler and the pigment are preferably added to different layers (for example, the first layer 12a, the second layer 12b, the third layer 12c, the fourth layer 12d, the polypropylene layer 11, etc.) described later.

[0081] From the viewpoint of more suitably exerting the effects of the present invention, the melting peak temperature of the polypropylene layer 11 is preferably about 140 °C or higher, more preferably about 145 °C or higher, and further preferably about 150 °C or higher. From the same viewpoint, this melting peak temperature is, for example, 180 °C or lower, preferably 175 °C or lower, more preferably 170 °C or lower, and further preferably about 165 °C or lower. As a preferable range of this melting peak temperature, about 140 to 180 °C, about 140 to 175 °C, about 140 to 170 °C, about 140 to 165 °C, about 145 to 180 °C, about 145 to 175 °C, about 145 to 170 °C, about 145 to 165 °C, about 150 to 180 °C, about 150 to 175 °C, about 150 to 170 °C, about 150 to 165 °C can be cited. In the present invention, the method for measuring the melting peak temperature is as described below.

[0082] <Measurement of melting peak temperature>

[0083] Regarding the adhesive film, the melting peak temperature is measured in accordance with the provisions of JIS K7121:2012 (Test method for the transition temperature of plastics (Addendum 1 to JIS K7121:1987)). The measurement is carried out using a differential scanning calorimeter. After the measurement sample is held at -50 °C for 15 minutes, it is heated from -50 °C to 210 °C at a heating rate of 10 °C / minute, and the first melting peak temperature P (°C) is measured. Then, it is held at 210 °C for 10 minutes. Next, it is cooled from 210 °C to -50 °C at a cooling rate of 10 °C / minute and held at -50 °C for 15 minutes. Further, it is heated from -50 °C to 210 °C at a heating rate of 10 °C / minute to measure the second melting peak temperature Q (°C). In addition, the flow rate of nitrogen is set to 50 ml / minute. Through the above steps, the first measured melting peak temperature P (°C) and the second measured melting peak temperature Q (°C) are obtained. The value of the first measured melting peak temperature P (°C) obtained through the above steps is adopted.

[0084] When the adhesive film 1 for metal terminals of the present invention is composed of a single layer of a polypropylene layer 11, the total thickness of the adhesive film 1 for metal terminals described later corresponds to the thickness of the polypropylene layer 11.

[0085] In addition, when the adhesive film 1 for metal terminals of the present invention is composed of multiple layers, from the viewpoint of more suitably exerting the effects of the present invention, the thickness of the polypropylene layer 11 is preferably about 10 μm or more, more preferably about 15 μm or more, and further preferably about 20 μm or more. In addition, it is preferably about 120 μm or less, more preferably about 100 μm or less, and further preferably 80 μm or less. As the preferred range of the thickness of the polypropylene layer 11, there can be mentioned about 10 to 120 μm, about 10 to 100 μm, about 10 to 80 μm, about 15 to 120 μm, about 15 to 100 μm, about 15 to 80 μm, about 20 to 120 μm, about 20 to 100 μm, about 20 to 80 μm. From the viewpoint of improving the insulation of the adhesive film for metal terminals, the thickness of the polypropylene layer 11 is preferably about 55 μm or more, more preferably about 60 μm or more. In addition, it is preferably about 100 μm or less, more preferably about 90 μm or less. As the preferred range, there can be mentioned about 55 to 100 μm, about 55 to 90 μm, about 60 to 100 μm, about 60 to 90 μm. In addition, when the adhesive film 1 for metal terminals of the present invention includes a plurality of polypropylene layers 11, the thickness of each polypropylene layer 11 is preferably the above-mentioned thickness respectively.

[0086] As described above, the adhesive film 1 for metal terminals of the present invention can be, for example, as Figures 5 to 7 shown, a structure in which at least a first layer 12a, a polypropylene layer 11, and a second layer 12b are laminated in this order. In this structure, the first layer 12a is disposed on the side of the outer packaging material 3 for electrical storage devices, and the second layer 12b is disposed on the side of the metal terminal 2. The polypropylene layer 11 is disposed between the first layer 12a and the second layer 12b and can form an intermediate layer. In Figures 5 to 7 the laminated structure, the first layer 12a and the second layer 12b are respectively located on the surfaces on both sides. In addition, in Figure 6 the laminated structure, a third layer 12c is provided between the polypropylene layer 11 and the second layer 12b. Although not shown in the figure, a fourth layer 12d can be provided between the first layer 12a and the polypropylene layer 11. When the adhesive film 1 for metal terminals of the present invention is composed of multiple layers, the adhesive film 1 for metal terminals is preferably composed of 3 to 6 layers, and preferably has at least a first layer 12a that forms the surface on the side of the outer packaging material 3 for electrical storage devices, a second layer 12b that forms the surface on the side of the metal terminal 2, and a polypropylene layer 11 located between the first layer 12a and the second layer 12b.

[0087] If the adhesive film 1 for the metal terminal of the present invention is disposed between the metal terminal 2 of the electrical storage device 10 and the exterior material 3 for the electrical storage device, the surface of the metal terminal 2 made of metal and the heat-sealable resin layer 35 (a layer formed of a heat-sealable resin such as polyolefin) of the exterior material 3 for the electrical storage device are adhered with the adhesive film 1 for the metal terminal interposed therebetween. The first layer 12a of the adhesive film 1 for the metal terminal is disposed on the side of the exterior material 3 for the electrical storage device, and the second layer 12b is disposed on the side of the metal terminal 2. The first layer 12a is in close contact with the heat-sealable resin layer 35 of the exterior material 3 for the electrical storage device, and the second layer 12b is in close contact with the metal terminal 2. The first layer 12a may be a single layer or multiple layers. In addition, the second layer 12b may be a single layer or multiple layers.

[0088] The first layer 12a, the second layer 12b, the third layer 12c, the fourth layer 12d, etc. contained in the adhesive film 1 for the metal terminal may be formed of resin films respectively. When the first layer 12a, the second layer 12b, the third layer 12c, the fourth layer 12d, etc. are formed of resin films respectively and the adhesive film 1 for the metal terminal of the present invention is manufactured by laminating the first layer 12a, the second layer 12b, the third layer 12c, the fourth layer 12d, etc. with a polypropylene layer 11, etc., the pre-formed resin films may be used as the first layer 12a, the second layer 12b, the third layer 12c, the fourth layer 12d, etc. respectively. In addition, the resins forming the first layer 12a, the second layer 12b, the third layer 12c, the fourth layer 12d, etc. may be respectively made into films on the surface of the polypropylene layer 11, etc. by extrusion molding or coating, etc., as the first layer 12a, the second layer 12b, the third layer 12c, the fourth layer 12d, etc. formed of resin films.

[0089] The first layer 12a, the second layer 12b, the third layer 12c, the fourth layer 12d, etc. contained in the adhesive film 1 for metal terminals can be made of resin respectively. As the resin constituting the first layer 12a, the second layer 12b, the third layer 12c, the fourth layer 12d, etc., for example, polyolefin resins, polyamide resins, polyester resins, epoxy resins, acrylic resins, fluororesins, silicone resins, phenolic resins, polyetherimide, polyimide, polycarbonate, and mixtures or copolymers thereof can be cited. Among these, polyolefin resins are particularly preferred. As polyolefin resins, polyolefins, acid-modified polyolefins, etc. can be cited. As polyolefins, specifically, polyethylene such as low-density polyethylene, medium-density polyethylene, high-density polyethylene, linear low-density polyethylene; crystalline or amorphous polypropylene such as homopolypropylene, block copolymers of polypropylene (for example, block copolymers of propylene and ethylene), random copolymers of polypropylene (for example, random copolymers of propylene and ethylene); ternary copolymers of ethylene-butene-propylene, etc. can be cited. Among these polyolefins, polyethylene and polypropylene are preferably cited, and polypropylene is more preferably cited. The resin forming the surface layer of the adhesive film 1 for metal terminals is preferably random polypropylene from the viewpoints of reducing the heat required for heat welding and shortening the heat welding time (sealing tightness viewpoints).

[0090] The first layer 12a disposed on the side of the outer packaging material 3 for electrical storage devices more preferably contains polyolefin as the main component, and further preferably contains polypropylene as the main component. Herein, as the main component, it means that among the resin components contained in the first layer 12a, the content rate is, for example, 50% by mass or more, preferably 60% by mass or more, more preferably 70% by mass or more, further preferably 80% by mass or more, further preferably 90% by mass or more, further preferably 95% by mass or more, further preferably 98% by mass or more, further preferably 99% by mass or more of the resin component. For example, the first layer 12a containing polypropylene as the main component means that among the resin components contained in the first layer 12a, the content rate of polypropylene is, for example, 50% by mass or more, preferably 60% by mass or more, more preferably 70% by mass or more, further preferably 80% by mass or more, further preferably 90% by mass or more, further preferably 95% by mass or more, further preferably 98% by mass or more, further preferably 99% by mass or more.

[0091] In addition, the second layer 12b disposed on the side of the metal terminal 2 more preferably contains an acid-modified polyolefin as the main component, and further preferably contains an acid-modified polypropylene as the main component. Herein, the main component refers to a resin component contained in the second layer 12b, and the content rate is, for example, 50% by mass or more, preferably 60% by mass or more, more preferably 70% by mass or more, further preferably 80% by mass or more, further preferably 90% by mass or more, further preferably 95% by mass or more, further preferably 98% by mass or more, and further preferably 99% by mass or more. For example, the second layer 12b containing an acid-modified polypropylene as the main component means that in the resin components contained in the second layer 12b, the content rate of the acid-modified polypropylene is, for example, 50% by mass or more, preferably 60% by mass or more, more preferably 70% by mass or more, further preferably 80% by mass or more, further preferably 90% by mass or more, further preferably 95% by mass or more, further preferably 98% by mass or more, and further preferably 99% by mass or more.

[0092] The melting peak temperatures of the first layer 12a, the second layer 12b, the third layer 12c, the fourth layer 12d, etc. are respectively preferably 125°C or higher, more preferably about 130°C or higher, and further preferably about 135°C or higher. The melting peak temperature is, for example, 180°C or lower, preferably 175°C or lower, more preferably 170°C or lower, further preferably about 165°C or lower, and further preferably about 160°C or lower. As the preferred range of the melting peak temperature, 125 - 180°C, 125 - 175°C, 125 - 170°C, 125 - 165°C, 125 - 160°C, 130 - 180°C, 130 - 175°C, 130 - 170°C, 130 - 165°C, 130 - 160°C, 135 - 180°C, 135 - 175°C, 135 - 170°C, 135 - 165°C, 135 - 160°C can be cited.

[0093] In addition, the thicknesses of the first layer 12a, the second layer 12b, the third layer 12c, the fourth layer 12d, etc. are respectively preferably about 10 μm or more, more preferably about 15 μm or more, and further preferably about 20 μm or more. In addition, they are preferably about 120 μm or less, more preferably about 100 μm or less, and further preferably 80 μm or less. As the preferred range of the thicknesses of the first layer 12a, the second layer 12b, the third layer 12c, the fourth layer 12d, etc., 10 - 120 μm, 10 - 100 μm, 10 - 80 μm, 15 - 120 μm, 15 - 100 μm, 15 - 80 μm, 20 - 120 μm, 20 - 100 μm, 20 - 80 μm can be cited.

[0094] In addition, in the first layer 12a, the second layer 12b, the third layer 12c, the fourth layer 12d, etc., known additives (the above-mentioned fillers, pigments, etc.) may be included in the same manner as in the polypropylene layer 11. Regarding the types or addition amounts of the fillers and pigments, they are the same as those in the polypropylene layer 11.

[0095] From the viewpoint of more suitably exerting the effects of the present invention, the total thickness of the adhesive film 1 for metal terminals is, for example, about 50 μm or more, preferably about 80 μm or more, more preferably about 90 μm or more, and further preferably about 100 μm or more. In addition, the total thickness of the adhesive film 1 for metal terminals of the present invention is about 500 μm or less, preferably about 300 μm or less, more preferably about 250 μm or less, and further preferably 200 μm or less. As the preferred range of the total thickness of the adhesive film 1 for metal terminals of the present invention, there may be mentioned about 50 to 500 μm, about 50 to 300 μm, about 50 to 250 μm, about 50 to 200 μm, about 80 to 500 μm, about 80 to 300 μm, about 80 to 250 μm, about 80 to 200 μm, about 90 to 500 μm, about 90 to 300 μm, about 90 to 250 μm, about 90 to 200 μm, about 100 to 500 μm, about 100 to 300 μm, about 100 to 250 μm, about 100 to 200 μm. As a more specific example, for instance, when the adhesive film 1 for metal terminals of the present invention is used in relatively small-sized electrical storage devices for mobile phones, smartphones, and tablets, the total thickness is preferably set to about 60 to 100 μm, and when used in relatively large-sized electrical storage devices for power energy storage systems and in-vehicle applications, the total thickness is preferably set to about 100 to 250 μm.

[0096] Further, from the viewpoint of more suitably exerting the effects of the present invention, the heat of fusion measured after heating the adhesive film 1 for metal terminals of the present invention under the conditions of a temperature of 200°C, a surface pressure of 0.25 MPa, and 16 seconds is preferably about 50 J / g or more, more preferably about 55 J / g or more, further preferably about 60 J / g or more, still further preferably 65 J / g or more. Additionally, it is preferably about 100 J / g or less, more preferably about 90 J / g or less, further preferably about 80 J / g or less. As the preferred range, values such as about 50 to 100 J / g, about 50 to 90 J / g, about 50 to 80 J / g, about 55 to 100 J / g, about 55 to 90 J / g, about 55 to 80 J / g, about 60 to 100 J / g, about 60 to 90 J / g, about 60 to 80 J / g, about 65 to 100 J / g, about 65 to 90 J / g, and about 65 to 80 J / g can be cited. The heat of fusion of the adhesive film after heating can be adjusted by controlling the content of polyethylene in the polypropylene film constituting the polypropylene layer 11, the polymerization form (homopolymerization, block, or random), and the film-forming conditions (temperature and speed during film formation, cooling temperature and speed, etc.). The method for measuring the heat of fusion of the adhesive film after heating is as described below.

[0097] <Measurement of Heat of Fusion of Adhesive Film after Heating>

[0098] The adhesive film 1 for metal terminals of the present invention is heated under the conditions of a temperature of 200°C, a surface pressure of 0.25 MPa, and 16 seconds. This heat treatment assumes the physical properties after the adhesive film is disposed between the exterior material for electrical storage devices and the metal terminals and heat-sealed. Then, the heat of fusion is measured in accordance with JIS K 7122:2012. The measurement is performed using a differential scanning calorimeter. After maintaining the adhesive film 1 for metal terminals after the heat treatment at -50°C for 15 minutes, it is heated from -50°C to 210°C at a heating rate of 10°C / minute, and the heat of fusion ΔH (J / g) for the first time is measured. Then, it is maintained at 210°C for 10 minutes. Next, it is cooled from 210°C to -50°C at a cooling rate of 10°C / minute and maintained at -50°C for 15 minutes. Further, it is heated from -50°C to 210°C at a heating rate of 10°C / minute, and the heat of fusion ΔH (J / g) for the second time is measured. In addition, the flow rate of nitrogen is set to 50 ml / minute. The value of the heat of fusion ΔH (J / g) measured for the first time through the above steps is used as the heat of fusion. The heat of fusion is the area enclosed by the baseline (a line formed by connecting the starting point and the ending point of the ridge line from the bottom line (base) to the bottom line) and the peak in the DSC curve.

[0099] Further, from the viewpoint of more suitably exerting the effects of the present invention, the water vapor transmission rate of the adhesive film 1 for metal terminals of the present invention is preferably about 5.10 g·mm / (m 2· day) or less, more preferably about 4.20 g·mm / (m 2 · day) or less, even more preferably about 4.10 g·mm / (m 2 · day) or less, even more preferably about 4.00 g·mm / (m 2 · day) or less. Additionally, for example, it is about 3.00 g·mm / (m 2 · day) or more, about 0 g·mm / (m 2 · day) or more. As the preferred range, 0 to 5.10 g·mm / (m 2 · day) or so, 0 to 4.20 g·mm / (m 2 · day) or so, 0 to 4.10 g·mm / (m 2 · day) or so, 0 to 4.00 g·mm / (m 2 · day) or so, 3.0 to 5.10 g·mm / (m 2 · day) or so, 3.00 to 4.20 g·mm / (m 2 · day) or so, 3.00 to 4.10 g·mm / (m 2 · day) or so, 3.00 to 4.00 g·mm / (m 2 · day) or so. The method for measuring the water vapor permeability of the adhesive film is as described below.

[0100] <Measurement of the water vapor permeability of the adhesive film>

[0101] First, through the following steps, prepare an outer package material for an electrical storage device (hereinafter, sometimes simply referred to as "outer package material"). For example, as the base material layer, prepare a biaxially stretched polyethylene terephthalate (PET) film (thickness 12 μm) and a stretched nylon (ONy) film (thickness 15 μm). Bond the PET film and the ONy film using a two-component polyurethane adhesive (a polyol compound and an aromatic isocyanate compound), and perform an aging treatment to obtain a base material layer (thickness 30 μm) formed by laminating a PET film (thickness 12 μm) / adhesive layer (cured thickness 3 μm) / ONy film (thickness 15 μm) in this order from the outside. Additionally, as the barrier layer, prepare an aluminum foil (JIS H4160: 1994 A8021H - O (thickness 40 μm)). Next, bond the surface of the ONy film side of the base material layer and the barrier layer using a two-component polyurethane adhesive (a polyol compound and an aromatic isocyanate compound), and perform an aging treatment to obtain a simulated outer package material for an electrical storage device (total thickness 73 μm) formed by laminating a base material layer (thickness 30 μm) / adhesive layer (cured thickness 3 μm) / barrier layer (thickness 40 μm) in this order, lacking the layer closer to the inside than the barrier layer.

[0102] Next, as Figure 9As shown in the schematic diagram, the obtained exterior material 3 is cut into a square with a longitudinal (MD) dimension of 120 mm and a transverse (TD) dimension of 120 mm ( Figure 9 as shown in (a)). In addition, prepare two pieces of the adhesive film 1 cut into a rectangle with a longitudinal (MD) dimension of 120 mm and a transverse (TD) dimension of 10 mm, and two pieces cut into a rectangle with a longitudinal (MD) dimension of 100 mm and a transverse (TD) dimension of 10 mm. On the barrier layer side of the exterior material 3, along the periphery of the exterior material 3, adhesive films with the same longitudinal length are arranged opposite to each other ( Figure 9 as shown in (b)). At this time, the second layer side of the adhesive film is made to be the barrier layer side of the exterior material 3. Next, a polytetrafluoroethylene film (PTFE film, thickness 100 μm) is placed on the adhesive film of this laminate (covering the surface of the adhesive film with the PTFE film), and it is placed on a press heated to 200 °C in the state of silicon wafer / PTFE / this laminate / PTFE / silicone sponge sheet, and left standing for 16 seconds under the condition of a pressure of 0.25 MPa to thermally bond the adhesive film and the exterior material 3. The thermally bonded laminate is naturally cooled to 25 °C, and the PTFE film is peeled off from the laminate. This heat treatment assumes the physical properties after the adhesive film is arranged between the exterior material for the electrical storage device and the metal terminal and is thermally bonded. Next, with the adhesive film on the inside, the exterior material 3 is folded in half longitudinally ( Figure 9 as shown in (c)). Two pieces of the adhesive film for the metal terminal with a longitudinal (MD) dimension of 120 mm are arranged overlapping each other between the exterior materials 3 along the long side to be heat-sealed as described later. Two pieces of the adhesive film for the metal terminal with a longitudinal (MD) dimension of 100 mm are arranged folded in half between the exterior materials 3 along the short side to be heat-sealed as described later. The peripheral part of the exterior material 3 becomes a laminate formed by laminating exterior material / adhesive film / adhesive film / exterior material in sequence ( Figure 9 as shown in (c)).

[0103] Next, using a heat-sealing bar (stainless steel plate), at the positions of the long side and the short side of the laminate, the layers of the laminate are thermally bonded to form a bag shape with one short side not thermally bonded ( Figure 9 as shown in (c)). The heat-sealing conditions are: for the long side, using a heat-sealing bar with a width of 7 mm, heat-sealing once under the conditions of a temperature of 190 °C, a surface pressure of 0.5 MPa, and 1.5 seconds ( Figure 9 as shown in s1 of (c)). In addition, for the short side, using a heat-sealing bar with a width of 7 mm, heat-sealing once under the conditions of a temperature of 190 °C, a surface pressure of 0.5 MPa, and 1.5 seconds ( Figure 9 as shown in s2 of (c)). It is dried in a drying chamber for 1 day. Then, from the position of the short side not thermally bonded, a liquid of ethylene carbonate:diethyl carbonate:dimethyl carbonate = 1:1:1 (volume ratio) (moisture content 0%) is injected, about 3.0 g ( Figure 9For the short sides without heat fusion in (d) above, heat sealing is also performed in the same manner as the above-mentioned short sides. Figure 9 A sealed bag is formed in s3 of (e) of Figure 9 (e) above. After leaving the sealed bag to stand for 30 days in an environment of a temperature of 65°C and a relative humidity of 90%, in a drying chamber, the moisture content of the liquid taken out from the sealed bag is measured by the Karl Fischer method to obtain the moisture content (ppm). From the obtained moisture content, the amount of electrolyte input (g), the permeation distance (mm), the permeation cross-sectional area (m 2 ), and the number of storage days (days), the water vapor transmission rate (g·mm / (m 2 ·day)) is calculated.

[0104] Water vapor transmission rate (g·mm / (m 2 ·day)) = [Obtained moisture content (ppm) × Amount of electrolyte input (g) × Permeation distance (mm)] / [Permeation cross-sectional area (m 2 ) × Number of storage days (days)]

[0105] · Obtained moisture content (ppm): Obtained by the Karl Fischer method.

[0106] · Amount of electrolyte input (g): 3.0 g

[0107] · Permeation distance (mm): Width of the sealed portion 7 mm

[0108] · Permeation cross-sectional area (m 2 ): Residual thickness (μm) × Inner circumference of the sealed portion (mm)

[0109] · Number of storage days (days): 30 days

[0110] [Base material]

[0111] In the adhesive film 1 for metal terminals, the base material is a layer that functions as a support for the adhesive film 1 for metal terminals and is provided as needed. For example, the polypropylene layer 11 can also be set as the base material. For example, in the case of the adhesive film 1 for metal terminals having the base material as an intermediate layer, a roll of the base material is prepared in advance, and using an extruder and a T-die casting device, polypropylene or the like is extruded onto the surface of the base material unwound from the roll at a specified thickness, whereby the adhesive film 1 for metal terminals having a multilayer structure can be manufactured.

[0112] The base material can be formed of the above-mentioned polypropylene layer 11 or can be formed of the above-mentioned first layer 12a, second layer 12b, third layer 12c, fourth layer 12d, etc.

[0113] The base material can be formed of, for example, a resin film. When manufacturing the adhesive film 1 for metal terminals of the present invention by laminating the base material with the first layer 12a or the like, a pre-formed resin film can also be used as the base material. In addition, the resin forming the base material can be made into a film on the surface of the first layer 12a or the like by extrusion molding or coating or the like, and used as the base material formed of a resin film.

[0114] There is no particular limitation on the raw material for forming the base material. Examples of the raw material for forming the base material 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 raw material for forming the base material is preferably a resin containing a polyolefin backbone such as polyolefin and acid-modified polyolefin. The fact that the resin constituting the base material contains a polyolefin backbone can be analyzed by, for example, infrared spectroscopy, gas chromatography-mass spectrometry, or the like.

[0115] The base material preferably contains a polyolefin resin, preferably contains polyolefin, and is further preferably a layer formed of polyolefin. The layer formed of polyolefin can be a stretched polyolefin film or an unstretched polyolefin film, but an unstretched polyolefin film is preferred. Specific examples of the polyolefin include polyethylene such as low-density polyethylene, medium-density polyethylene, high-density polyethylene, and linear low-density polyethylene; crystalline or amorphous polypropylene such as homopolypropylene, block copolymers of polypropylene (for example, block copolymers of propylene and ethylene), and random copolymers of polypropylene (for example, random copolymers of propylene and ethylene); and terpolymers of ethylene-butene-propylene. Among these polyolefins, polyethylene and polypropylene are preferably mentioned, and polypropylene is more preferably mentioned. In addition, since the base material has excellent electrolyte resistance, it preferably contains homopolypropylene, is more preferably formed of homopolypropylene, and is further preferably an unstretched homopolypropylene film.

[0116] As polyamides, specifically, examples 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 copolyamides such as nylon 6I, nylon 6T, nylon 6IT, and nylon 6I6T (I represents isophthalic acid, T represents terephthalic acid), and polyamides containing aromatic groups such as poly(m-xylylene adipamide) (MXD6); alicyclic polyamides such as poly(aminomethylcyclohexyladipamide) (PACM6); polyamides copolymerized with lactam components or isocyanate components such as 4,4'-diphenylmethane-diisocyanate, polyester amide copolymers or polyether ester amide copolymers as copolymers of copolyamides and polyesters or polyalkylene ether diols; copolymers thereof, etc. These polyamides can be used alone or in combination of two or more.

[0117] As polyesters, specifically, examples include polyethylene terephthalate, polybutylene terephthalate, polyethylene naphthalate, polybutylene naphthalate, poly(ethylene isophthalate), copolyester having polyethylene terephthalate as the main repeating unit, copolyester having polybutylene terephthalate as the main repeating unit, etc. In addition, as copolyester having polyethylene terephthalate as the main repeating unit, specifically, examples include: copolyester obtained by polymerizing polyethylene terephthalate as the main repeating unit and polyethylene isophthalate (hereinafter abbreviated in accordance with polyethylene glycol (terephthalate / isophthalate)), polyethylene (terephthalate / isophthalate), polyethylene (terephthalate / adipate), polyethylene (terephthalate / sodium isophthalate sulfonate), polyethylene (terephthalate / sodium isophthalate sulfonate), polyethylene (terephthalate / phenyl-dicarboxylate), polyethylene (terephthalate / decanedicarboxylate), etc. In addition, as copolyester having polybutylene terephthalate as the main repeating unit, specifically, examples include copolyester obtained by polymerizing polybutylene terephthalate as the main repeating unit and polybutylene isophthalate (hereinafter abbreviated in accordance with polybutylene glycol (terephthalate / isophthalate)), polybutylene glycol (terephthalate / adipate), polybutylene glycol (terephthalate / sebacate), polybutylene glycol (terephthalate / decanedicarboxylate), polybutylene naphthalate, etc. These polyesters can be used alone or in combination of two or more.

[0118] In addition, the substrate can be formed of a nonwoven fabric made of the above resins. When the substrate is a nonwoven fabric, the substrate is preferably composed of the above polyolefin resins, polyamide resins, etc.

[0119] The melting peak temperature of the base material is preferably 120 °C or higher, more preferably about 130 °C or higher, and further preferably about 140 °C or higher. From the same perspective, the melting peak temperature is, for example, 210 °C or lower, preferably 200 °C or lower, more preferably 190 °C or lower, further preferably about 180 °C or lower, and further preferably about 170 °C or lower. As the preferred range of the melting peak temperature, 120 - 210 °C or so, 120 - 200 °C or so, 120 - 190 °C or so, 120 - 180 °C or so, 120 - 170 °C or so, 130 - 210 °C or so, 130 - 200 °C or so, 130 - 190 °C or so, 130 - 180 °C or so, 130 - 170 °C or so, 140 - 210 °C or so, 140 - 200 °C or so, 140 - 190 °C or so, 140 - 180 °C or so, 140 - 170 °C or so can be cited.

[0120] The base material can be a single layer or multiple layers.

[0121] In addition, by incorporating a colorant in the base material, it is also possible to form a layer containing the colorant in the base material. In addition, a resin with low transparency can be selected to adjust the light transmittance. When the base material is a film, a colored film or a film with low transparency can also be used. In addition, when the base material is a non-woven fabric, fibers containing a colorant or a non-woven fabric using an adhesive, or a non-woven fabric with low transparency can be used.

[0122] When the base material is composed of a resin film, known adhesion-promoting means such as corona discharge treatment, ozone treatment, plasma treatment, etc. can be performed on the surface of the base material as needed.

[0123] In addition, from the perspective of more suitably exerting the effects of the present invention, the thickness of the base material is preferably about 20 μm or more, more preferably about 30 μm or more, and further preferably about 40 μm or more. In addition, it is preferably about 120 μm or less, more preferably about 110 μm or less, and further preferably 100 μm or less. As the preferred range of the thickness of the base material, 20 - 120 μm or so, 20 - 110 μm or so, 20 - 100 μm or so, 30 - 120 μm or so, 30 - 110 μm or so, 30 - 100 μm or so, 40 - 120 μm or so, 40 - 110 μm or so, 40 - 100 μm or so can be cited.

[0124] [Adhesion Promoter Layer 13]

[0125] The adhesion promoter layer 13 is a layer provided as needed, for example, for the purpose of firmly bonding the polypropylene layer 11 to the first layer 12a and the polypropylene layer 11 to the second layer 12b (refer to Figure 7)。The adhesion promoter layer 13 can be provided only on one side between the polypropylene layer 11 and the first layer 12a and the second layer 12b, or can be provided on both sides.

[0126] 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 adhesion promoters. From the viewpoint of obtaining strong adhesion strength, among these, it is preferably formed from an isocyanate-based adhesion promoter. As the isocyanate-based adhesion promoter, an adhesion promoter composed of an isocyanate component selected from triisocyanate monomers and polymeric MDI has excellent lamination strength and little reduction in lamination strength at high temperatures. In particular, it is particularly preferred to use an adhesion promoter composed of triphenylmethane-4,4′,4″-triisocyanate as a triisocyanate monomer or polymethylene polyphenyl polyisocyanate as polymeric MDI (NCO content rate is about 30%, viscosity is 200 to 700 mPa·s). In addition, it is also preferred to use tris(p-isocyanatophenyl) thiophosphate as a triisocyanate monomer or a two-component curable adhesion promoter with a polyethyleneimine-based main agent and polycarbodiimide as a crosslinking agent to form.

[0127] The adhesion promoter layer 13 can be formed by coating and drying using known coating methods such as bar coating, roll coating, and gravure coating. As the coating amount of the adhesion promoter, in the case of an adhesion promoter composed of triisocyanate, it is about 20 to 100 mg / m 2 preferably about 40 to 60 mg / m 2 in the case of an adhesion promoter composed of polymeric MDI, it is about 40 to 150 mg / m 2 preferably about 60 to 100 mg / m 2 in the case of a two-component curable adhesion promoter with a polyethyleneimine-based main agent and polycarbodiimide as a crosslinking agent, it is about 5 to 50 mg / m 2 preferably about 10 to 30 mg / m 2 In addition, the triisocyanate monomer is a monomer having three isocyanate groups in one molecule, and polymeric MDI is a mixture of MDI and MDI oligomers polymerized from MDI, and is represented by the following formula.

[0128]

[0129] From the viewpoint of more suitably exerting the effects of the present invention, it is preferred that the first layer 12a is in surface contact with the polypropylene layer 11, and the second layer 12b is in surface contact with the polypropylene layer 11.

[0130] As a specific example of the preferred laminated structure of the adhesive film 1 for metal terminals of the present invention, the following can be cited: a three-layer structure formed by sequentially laminating a first layer 12a made of polypropylene / a polypropylene layer 11 made of polypropylene / a second layer 12b made of acid-modified polypropylene; a three-layer structure formed by sequentially laminating a first layer 12a made of acid-modified polypropylene / a polypropylene layer 11 made of polypropylene / a second layer 12b made of acid-modified polypropylene; a four-layer structure formed by sequentially laminating a first layer 12a made of polypropylene / a polypropylene layer 11 made of polypropylene / a third layer 12c made of polypropylene / a second layer 12b made of acid-modified polypropylene; a four-layer structure formed by sequentially laminating a first layer 12a made of acid-modified polypropylene / a polypropylene layer 11 made of polypropylene / a third layer 12c made of polypropylene / a second layer 12b made of acid-modified polypropylene, etc.

[0131] The adhesive film 1 for metal terminals of the present invention is preferably formed of a polyolefin resin. For example, the resin component contained in the adhesive film 1 for metal terminals of the present invention is preferably only a polyolefin resin, more preferably only an acid-modified polyolefin and a polyolefin, and further preferably only an acid-modified polypropylene and a polypropylene. The preferred acid-modified polyolefin and polyolefin are as described above respectively.

[0132] As a method for making the adhesive film 1 for metal terminals exist between the metal terminal 2 and the exterior material 3 for electrical storage devices, there is no particular limitation. For example, as Figures 1 to 3 shown, in the portion where the metal terminal 2 is clamped by the exterior material 3 for electrical storage devices, the adhesive film 1 for metal terminals can be wound around the metal terminal 2. Additionally, omitting the illustration, in the portion where the metal terminal 2 is clamped by the exterior material 3 for electrical storage devices, the adhesive film 1 for metal terminals can be disposed on both sides of the metal terminal 2 in a manner that straddles two metal terminals 2.

[0133] [Metal terminal 2]

[0134] The adhesive film 1 for metal terminals of the present invention is used between the metal terminal 2 and the exterior material 3 for electrical storage devices. The metal terminal 2 (tab) is a conductive component electrically connected to the electrode (positive electrode or negative electrode) of the electrical storage device element 4 and is made of a metal material. There is no particular limitation on the metal material constituting the metal terminal 2. For example, aluminum, nickel, copper, etc. can be cited. For example, the metal terminal 2 connected to the positive electrode of a lithium-ion electrical storage device is usually made of aluminum, etc. Additionally, the metal terminal 2 connected to the negative electrode of a lithium-ion electrical storage device is usually made of copper, nickel, etc.

[0135] From the viewpoint of improving electrolyte resistance, it is preferable to perform a chemical surface treatment on the surface of the metal terminal 2. For example, when the metal terminal 2 is formed of aluminum, as a specific example of the chemical surface treatment, known methods for forming a corrosion-resistant coating film such as phosphate, chromate, fluoride, triazine thiol compound, etc. can be cited. Among the methods for forming a corrosion-resistant coating film, a phosphoric acid chromate treatment using a substance composed of three components of phenolic resin, chromium(III) fluoride compound, and phosphoric acid is also suitable.

[0136] The size of the metal terminal 2 can be appropriately set according to the size of the electrical storage device used, etc. As the thickness of the metal terminal 2, it can be cited that it is preferably about 50 to 1000 μm, more preferably about 70 to 800 μm. In addition, as the length of the metal terminal 2, it can be cited that it is preferably about 1 to 200 mm, more preferably about 3 to 150 mm. In addition, as the width of the metal terminal 2, it can be cited that it is preferably about 1 to 200 mm, more preferably about 3 to 150 mm.

[0137] [Outer packaging material 3 for electrical storage device]

[0138] As the outer packaging material 3 for the electrical storage device, a material having a laminated structure formed of a laminate having at least a base material layer 31, a barrier layer 33, and a heat-sealable resin layer 35 in this order can be cited. Figure 8 In an example of the cross-sectional structure of the outer packaging material 3 for the electrical storage device, a method in which a base material layer 31, an adhesive layer 32 provided as needed, a barrier layer 33, an adhesive layer 34 provided as needed, and a heat-sealable resin layer 35 are laminated in this order is shown. In the outer packaging material 3 for the electrical storage device, the base material layer 31 is on the outer layer side, and the heat-sealable resin layer 35 is on the innermost layer. When assembling the electrical storage device, the heat-sealable resin layers 35 located at the periphery of the electrical storage device element 4 are brought into surface contact with each other for heat sealing, thereby sealing the electrical storage device element 4 and encapsulating the electrical storage device element 4. In addition, in Figures 1 to 3 the electrical storage device 10 when using the embossed type outer packaging material 3 for the electrical storage device obtained by molding such as embossing is shown, but the outer packaging material 3 for the electrical storage device can also be an unformed bag type. In addition, among the bag types, there are three-side seals, four-side seals, pillow types, etc., and any type can be used.

[0139] The thickness of the laminate that constitutes the exterior material 3 for the electrical storage device is not particularly limited. Regarding the upper limit, from the viewpoints of cost reduction and energy density improvement, for example, it can be about 190 μm or less, preferably about 180 μm or less, about 160 μm or less, about 155 μm or less, about 140 μm or less, about 130 μm or less, about 120 μm or less. Regarding the lower limit, from the viewpoint of maintaining the function of the exterior material 3 for the electrical storage device such as protecting the electrical storage device element 4, it is preferably about 35 μm or more, about 45 μm or more, about 60 μm or more, about 80 μm or more. Regarding the preferred range, for example, it can be about 35 - 190 μm, about 35 - 180 μm, about 35 - 160 μm, about 35 - 155 μm, about 35 - 140 μm, about 35 - 130 μm, about 35 - 120 μm, about 45 - 190 μm, about 45 - 180 μm, about 45 - 160 μm, about 45 - 155 μm, about 45 - 140 μm, about 45 - 130 μm, about 45 - 120 μm, about 60 - 190 μm, about 60 - 180 μm, about 60 - 160 μm, about 60 - 155 μm, about 60 - 140 μm, about 60 - 130 μm, about 60 - 120 μm, about 80 - 190 μm, about 80 - 180 μm, about 80 - 160 μm, about 80 - 155 μm, about 80 - 140 μm, about 80 - 130 μm, about 80 - 120 μm.

[0140] (Base material layer 31)

[0141] In the exterior material 3 for the electrical storage device, the base material layer 31 is a layer that functions as the base material of the exterior material for the electrical storage device and is the layer that forms the outermost layer side.

[0142] Regarding the raw material for forming the base material layer 31, it is not particularly limited as long as it has insulation properties. As the raw material for forming the base material layer 31, for example, polyester, polyamide, epoxy, acrylic resin, fluororesin, polyurethane, silicone resin, phenol resin, polyetherimide, polyimide, and mixtures or copolymers thereof can be listed. Polyesters such as polyethylene terephthalate and polybutylene terephthalate have the advantages of excellent electrolyte resistance and being less likely to turn white due to the attachment of the electrolyte, and are suitable for use as the raw material for forming the base material layer 31. In addition, the polyamide film has excellent stretchability and can prevent the occurrence of whitening caused by resin cracking of the base material layer 31 during molding, and is suitable for use as the raw material for forming the base material layer 31.

[0143] The base material layer 31 can be formed of a resin film that is uniaxially or biaxially stretched, or can also be formed of an unstretched resin film. Among them, a resin film that is uniaxially or biaxially stretched, particularly a biaxially stretched resin film, has improved heat resistance through orientation crystallization, and thus is suitable for use as the base material layer 31.

[0144] Among these, as the resin film forming the base material layer 31, nylon and polyester are preferably listed, and biaxially stretched nylon and biaxially stretched polyester are more preferably listed.

[0145] In the base material layer 31, in order to improve the pinhole resistance and insulation when used as a package for an electrical storage device, resin films of different raw materials can also be laminated. Specifically, a multilayer structure formed by laminating a polyester film and a nylon film, a multilayer structure formed by laminating a biaxially stretched polyester and a biaxially stretched nylon, etc. can be listed. When the base material layer 31 is made into a multilayer structure, the respective resin films can be bonded via an adhesive, or can also be directly laminated without an adhesive. In the case of not bonding via an adhesive, for example, methods of bonding in a thermally molten state such as coextrusion method, sandwich lamination method, and thermal lamination method can be listed.

[0146] In addition, the base material layer 31 can be made to have low friction in order to improve formability. When the base material layer 31 is made to have low friction, there is no particular limitation on the coefficient of friction of its surface. For example, 1.0 or less can be listed. In order to make the base material layer 31 have low friction, for example, matting treatment, formation of a thin film layer of a slip agent, a combination of these, etc. can be listed.

[0147] Regarding the thickness of the base material layer 31, for example, about 10 to 50 μm, preferably about 15 to 30 μm can be listed.

[0148] (Adhesive layer 32)

[0149] In the exterior material 3 for an electrical storage device, the adhesive layer 32 is a layer that is disposed on the base material layer 31 as needed in order to impart adhesiveness to the base material layer 31. That is, the adhesive layer 32 is provided between the base material layer 31 and the barrier layer 33.

[0150] The adhesive layer 32 is formed of an adhesive that can bond the base material layer 31 and the barrier layer 33. The adhesive used in the formation of the adhesive layer 32 can be a two-component curable adhesive, or can also be a one-component curable adhesive. In addition, there is no particular limitation on the bonding mechanism of the adhesive used in the formation of the adhesive layer 32, and it can be any mechanism such as chemical reaction type, solvent evaporation type, thermal melting type, hot pressing type, etc.

[0151] As the resin component of the adhesive that can be used in the formation of the adhesive layer 32, from the viewpoints of excellent spreadability, durability under high humidity conditions, yellowing inhibition effect, heat deterioration inhibition effect during heat sealing, etc., and effectively suppressing the occurrence of delamination by suppressing the decrease in the lamination strength between the base material layer 31 and the barrier layer 33, the following are preferably listed: two-component curable polyurethane adhesives; polyamides, polyesters, or blended resins of these with modified polyolefins.

[0152] In addition, the adhesive layer 32 can also be multi-layered with different adhesive components. In the case of multi-layerizing the adhesive layer 32 with different adhesive components, from the viewpoint of improving the lamination strength between the base material layer 31 and the barrier layer 33, it is preferable to select a resin with excellent adhesiveness to the base material layer 31 as the adhesive component disposed on the side of the base material layer 31, and select an adhesive component with excellent adhesiveness to the barrier layer 33 as the adhesive component disposed on the side of the barrier layer 33. In the case of multi-layerizing the adhesive layer 32 with different adhesive components, specifically, as the adhesive component disposed on the side of the barrier layer 33, the following are preferably listed: resins including acid-modified polyolefins, metal-modified polyolefins, mixed resins of polyesters and acid-modified polyolefins, copolyester resins, etc.

[0153] Regarding the thickness of the adhesive layer 32, for example, it can be about 2 to 50 μm, preferably about 3 to 25 μm.

[0154] (Barrier layer 33)

[0155] In the exterior material 3 for electric storage devices, the barrier layer 33 is a layer that, in addition to improving the strength of the exterior material for electric storage devices, also has the function of preventing the intrusion of water vapor, oxygen, light, etc. into the interior of the electric storage device. The barrier layer 33 is preferably a metal layer, that is, a layer formed of a metal. Specifically, as the metal constituting the barrier layer 33, aluminum, stainless steel, titanium, etc. can be listed, and aluminum is preferably listed. The barrier layer 33 can be formed, for example, by a metal foil, a metal vapor deposition film, an inorganic oxide vapor deposition film, a carbon-containing inorganic oxide vapor deposition film, a film provided with these vapor deposition films, etc., and is preferably formed by a metal foil, and more preferably formed by an aluminum foil. In the manufacture of the exterior material for electric storage devices, from the viewpoint of preventing wrinkles or pinholes from occurring in the barrier layer 33, the barrier layer is more preferably formed of 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), etc.

[0156] Regarding the thickness of the barrier layer 33, from the viewpoints of thinning the exterior material for the electrical storage device and making it less likely to generate pinholes even after molding, values around 10 to 200 μm are preferably cited, more preferably around 20 to 100 μm, around 20 to 45 μm, around 45 to 65 μm, and around 65 to 85 μm.

[0157] In addition, for the stabilization of adhesion and the prevention of dissolution or corrosion, etc., the barrier layer 33 is preferably surface-treated by a chemical method on at least one surface, preferably on both surfaces. Here, the chemical surface treatment refers to a treatment for forming a corrosion-resistant coating film on the surface of the barrier layer.

[0158] (Adhesive layer 34)

[0159] In the exterior material 3 for the electrical storage device, the adhesive layer 34 is a layer provided between the barrier layer 33 and the heat-sealable resin layer 35 as needed to firmly bond the heat-sealable resin layer 35.

[0160] The adhesive layer 34 is formed by an adhesive capable of bonding the barrier layer 33 and the heat-sealable resin layer 35. There is no particular limitation on the composition of the adhesive used for forming the adhesive layer. For example, a resin composition containing an acid-modified polyolefin can be cited. As the acid-modified polyolefin, the same substances as those exemplified in the first layer 12a and the second layer 12b can be exemplified.

[0161] Regarding the thickness of the adhesive layer 34, for example, values around 1 to 40 μm can be cited, preferably around 2 to 30 μm.

[0162] (Heat-sealable resin layer 35)

[0163] In the exterior material 3 for the electrical storage device, the heat-sealable resin layer 35 corresponds to the innermost layer and is a layer that heat-seals the electrical storage device elements by heat-sealing heat-sealable resin layers to each other during the assembly of the electrical storage device.

[0164] Regarding the resin component used for the heat-sealable resin layer 35, there is no particular limitation as long as it can be heat-sealed. For example, polyolefins and cyclic polyolefins can be cited.

[0165] Specifically, as the above polyolefins, the following can be cited: polyethylene such as low-density polyethylene, medium-density polyethylene, high-density polyethylene, and linear low-density polyethylene; crystalline or amorphous polypropylene such as homopolypropylene, block copolymers of polypropylene (e.g., block copolymers of propylene and ethylene), and random copolymers of polypropylene (e.g., random copolymers of propylene and ethylene); and terpolymers of ethylene - butene - propylene. Among these polyolefins, polyethylene and polypropylene are also preferably cited.

[0166] The above-mentioned cyclic polyolefin is a copolymer of an olefin and a cyclic monomer. Examples of the olefin as a constituent monomer of the above-mentioned cyclic polyolefin include ethylene, propylene, 4-methyl-1-pentene, butadiene, isoprene, etc. In addition, examples of the cyclic monomer as a constituent monomer of the above-mentioned cyclic polyolefin include cyclic olefins such as norbornene; specifically, cyclic dienes such as cyclopentadiene, dicyclopentadiene, cyclohexadiene, norbornadiene, etc. Among these polyolefins, cyclic olefins can be preferably cited, and norbornene is further preferred. Styrene can also be cited as a constituent monomer.

[0167] Among these resin components, crystalline or amorphous polyolefins, cyclic polyolefins, and blend polymers thereof are also preferably cited; polyethylene, polypropylene, copolymers of ethylene and norbornene, and blend polymers of two or more of these are further preferred.

[0168] The heat-sealable resin layer 35 can be formed of only one resin component alone, or can be formed of a blend polymer composed of a combination of two or more resin components. In addition, the heat-sealable resin layer 35 can be formed of only one layer, but can also be formed of two or more layers of the same or different resin components. If the resin of the second layer 12b is common to the resin of the heat-sealable resin layer 35, the adhesion between these layers is improved, which is particularly preferred.

[0169] In addition, the thickness of the heat-sealable resin layer 35 is not particularly limited, and examples include about 2 to 2000 μm, preferably about 5 to 1000 μm, and further preferably about 10 to 500 μm. In addition, the thickness of the heat-sealable resin layer 35, for example, can be cited as about 100 μm or less, preferably about 85 μm or less, and more preferably about 15 to 85 μm. In addition, for example, when the thickness of the adhesive layer 34 described later is 10 μm or more, the thickness of the heat-sealable resin layer 35 can be preferably cited as about 85 μm or less, and more preferably about 15 to 45 μm. For example, when the thickness of the adhesive layer 34 described later is less than 10 μm or when the adhesive layer 34 is not provided, the thickness of the heat-sealable resin layer 35 can be preferably cited as about 20 μm or more, and more preferably about 35 to 85 μm.

[0170] The exterior material for an electric storage device of the present invention can also be in the form of a kit including the exterior material for an electric storage device for an electric storage device and the adhesive film for metal terminals of the present invention. In this case, the electric storage devices to which it applies include: an electric storage device element having at least a positive electrode, a negative electrode, and an electrolyte; an exterior material for an electric storage device encapsulating the electric storage device element; and metal terminals that are electrically connected to the positive electrode and the negative electrode respectively and protrude to the outside of the exterior material for an electric storage device. When using the kit of the present invention, it is used in such a manner that the adhesive film for metal terminals of the present invention is located between the metal terminal and the exterior material for an electric storage device.

[0171] 2. Electrical Storage Device

[0172] The electrical storage device 10 of the present invention includes: an electrical storage device element 4 having at least a positive electrode, a negative electrode, and an electrolyte; an outer packaging material 3 for the electrical storage device that encapsulates the electrical 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 outer packaging material 3 for the electrical storage device. In the electrical storage device 10 of the present invention, it is characterized in that there is a bonding film 1 for the metal terminal of the present invention between the metal terminal 2 and the outer packaging material 3 for the electrical storage device. That is, the electrical storage device 10 of the present invention can be manufactured by a method including a process of making the bonding film 1 for the metal terminal of the present invention exist between the metal terminal 2 and the outer packaging material 3 for the electrical storage device.

[0173] Specifically, by using the outer packaging material 3 for the electrical storage device to encapsulate the electrical storage device element 4 having at least a positive electrode, a negative electrode, and an electrolyte in a state where the metal terminals 2 connected to the positive electrode and the negative electrode respectively protrude to the outside, and making the bonding film 1 for the metal terminal of the present invention be located between the metal terminal 2 and the heat-sealable resin layer 35, and encapsulating in such a way that a flange portion (a region where the heat-sealable resin layers 35 are in contact with each other, the peripheral portion 3a of the outer packaging material 3 for the electrical storage device) of the outer packaging material 3 for the electrical storage device can be formed at the periphery of the electrical storage device element 4, and heat-sealing the heat-sealable resin layers 35 of the flange portion to seal them, an electrical storage device 10 using the outer packaging material 3 for the electrical storage device can be provided. In addition, when using the outer packaging material 3 for the electrical storage device to accommodate the electrical storage device element 4, it is used in such a way that the heat-sealable resin layer 35 of the outer packaging material 3 for the electrical storage device becomes the inner side (the surface in contact with the electrical storage device element 4).

[0174] The outer packaging material for the electrical storage device of the present invention can be suitably used for electrical storage devices such as batteries (including condensers, capacitors, etc.). Moreover, the outer packaging material for the electrical storage device of the present invention can be used for either a primary battery or a secondary battery, and is preferably a secondary battery. Regarding the types of secondary batteries to which the outer packaging material for the electrical storage device of the present invention can be applied, there is no particular limitation. For example, lithium-ion batteries, lithium-ion polymer batteries, all-solid batteries, semi-solid batteries, quasi-solid batteries, polymer batteries, all-resin batteries, lead-acid batteries, nickel-metal hydride batteries, nickel-cadmium batteries, nickel-iron batteries, nickel-zinc batteries, silver oxide-zinc batteries, metal-air batteries, polyvalent cation batteries, condensers, capacitors, etc. can be listed. Among these secondary batteries, lithium-ion batteries and lithium-ion polymer batteries can also be listed as preferred application objects of the outer packaging material for the electrical storage device of the present invention.

[0175] Examples

[0176] Examples and comparative examples are listed below to describe the present invention in detail. However, the present invention is not limited to the examples.

[0177] <Manufacture of Adhesive Film for Metal Terminals>

[0178] Example 1

[0179] Using an extruder and a T-die casting device, on one surface of a polypropylene film (CPP layer (unstretched homopolypropylene layer), melting peak temperature 160 °C, thickness 80 μm) as the polypropylene layer, maleic anhydride-modified polypropylene (r-PPa layer (maleic anhydride-modified random polypropylene layer), melting peak temperature 140 °C) as the second layer on the metal terminal side was extruded with a thickness of 60 μm, and on the other surface, polypropylene (r-PP layer (random polypropylene layer), melting peak temperature 140 °C) as the first layer on the exterior material side was extruded with a thickness of 60 μm, to obtain an adhesive film (total thickness 200 μm) formed by laminating the first layer (r-PP layer, thickness 60 μm) / polypropylene layer (CPP layer, thickness 80 μm) / second layer (r-PPa layer, thickness 60 μm) in sequence.

[0180] In the adhesive films of each example and comparative example, the island ratio of the sea-island structure of the polypropylene layer, the soft segment component ratio of the adhesive film, and the heat of fusion after heating of the adhesive film were adjusted by controlling the content of polyethylene in the polypropylene film, the polymerization form (homopolymerization, block or random), and the film-forming conditions (temperature and speed during film formation, cooling temperature and speed, etc.).

[0181] Example 2

[0182] Using an extruder and a T-die casting device, on one surface of a polypropylene film (CPP layer (unstretched homopolypropylene layer), melting peak temperature 160 °C, thickness 50 μm) as the polypropylene layer, maleic anhydride-modified polypropylene (r-PPa layer (maleic anhydride-modified random polypropylene layer), melting peak temperature 140 °C) as the second layer on the metal terminal side was extruded with a thickness of 100 μm, and on the other surface, polypropylene (r-PP layer (random polypropylene layer), melting peak temperature 140 °C) as the first layer on the exterior material side was extruded with a thickness of 50 μm, to obtain an adhesive film (total thickness 200 μm) formed by laminating the first layer (r-PP layer (random polypropylene layer), thickness 50 μm) / polypropylene layer (CPP layer, thickness 50 μm) / second layer (r-PPa layer, thickness 100 μm) in sequence.

[0183] Example 3

[0184] Using an extruder and a T-die casting device, on one surface of a polypropylene film (CPP layer (unstretched homopolypropylene layer), melting peak temperature 160 °C, thickness 80 μm) as the polypropylene layer, maleic anhydride-modified polypropylene (r-PPa layer (maleic anhydride-modified random polypropylene layer), melting peak temperature 140 °C) as the second layer on the metal terminal side and maleic anhydride-modified polypropylene (h-PPa layer (maleic anhydride-modified homopolypropylene layer), melting peak temperature 160 °C) as the third layer located between the polypropylene layer and the second layer are extruded with thicknesses of 40 μm and 20 μm respectively. Additionally, on the other surface of the polypropylene film as the polypropylene layer, polypropylene (r-PP layer (random polypropylene layer), melting peak temperature 140 °C) is extruded with a thickness of 60 μm as the first layer on the exterior material side, obtaining an adhesive film (total thickness 200 μm) with the first layer (r-PP layer, thickness 60 μm) / polypropylene layer (CPP layer, thickness 80 μm) / third layer (h-PPa layer, thickness 20 μm) / second layer (r-PPa layer, thickness 40 μm) laminated in sequence.

[0185] Example 4

[0186] Using an extruder and a T-die casting device, on one surface of a polypropylene film (CPP layer (unstretched homopolypropylene layer), melting peak temperature 160 °C, thickness 80 μm) as the polypropylene layer, maleic anhydride-modified polypropylene (r-PPa layer (maleic anhydride-modified random polypropylene layer), melting peak temperature 140 °C) as the second layer on the metal terminal side and maleic anhydride-modified polypropylene (h-PPa layer (maleic anhydride-modified homopolypropylene layer), melting peak temperature 160 °C) as the third layer located between the polypropylene layer and the second layer are extruded with thicknesses of 30 μm respectively. Additionally, on the other surface of the polypropylene film as the polypropylene layer, polypropylene (r-PP layer (random polypropylene layer), melting peak temperature 140 °C) is extruded with a thickness of 60 μm as the first layer on the exterior material side, obtaining an adhesive film (total thickness 200 μm) with the first layer (r-PP layer, thickness 60 μm) / polypropylene layer (CPP layer, thickness 80 μm) / third layer (h-PPa layer, thickness 30 μm) / second layer (r-PPa layer, thickness 30 μm) laminated in sequence.

[0187] Example 5

[0188] Using an extruder and a T-die casting device, on one surface of a polypropylene film (CPP layer (unstretched homopolypropylene layer), melting peak temperature 160°C, thickness 40 μm) as the polypropylene layer, maleic anhydride-modified polypropylene (r-PPa layer (maleic anhydride-modified random polypropylene layer), melting peak temperature 140°C) as the second layer on the metal terminal side is extruded with a thickness of 20 μm, and on the other surface, polypropylene (r-PP layer (random polypropylene layer), melting peak temperature 140°C) as the first layer on the outer packaging material side is extruded with a thickness of 20 μm, to obtain an adhesive film (total thickness 80 μm) formed by laminating in sequence the first layer (r-PP layer, thickness 20 μm) / polypropylene layer (CPP layer, thickness 40 μm) / second layer (r-PPa layer, thickness 20 μm).

[0189] Example 6

[0190] Using an extruder and a T-die casting device, on one surface of a polypropylene film (CPP layer (unstretched homopolypropylene layer), melting peak temperature 160°C, thickness 30 μm) as the polypropylene layer, maleic anhydride-modified polypropylene (r-PPa layer (maleic anhydride-modified random polypropylene layer), melting peak temperature 140°C) as the second layer on the metal terminal side is extruded with a thickness of 25 μm, and on the other surface, polypropylene (r-PP layer (random polypropylene layer), melting peak temperature 140°C) as the first layer on the outer packaging material side is extruded with a thickness of 25 μm, to obtain an adhesive film (total thickness 80 μm) formed by laminating in sequence the first layer (r-PP layer, thickness 25 μm) / polypropylene layer (CPP layer, thickness 30 μm) / second layer (r-PPa layer, thickness 25 μm).

[0191] Example 7

[0192] Using an extruder and a T-die casting device, on one surface of a polypropylene film (CPP layer (unstretched homopolypropylene layer), melting peak temperature 160°C, thickness 30 μm) as the polypropylene layer, maleic anhydride-modified polypropylene (r-PPa layer (maleic anhydride-modified random polypropylene layer), melting peak temperature 140°C) as the second layer on the metal terminal side is extruded with a thickness of 20 μm, and on the other surface, polypropylene (r-PP layer (random polypropylene layer), melting peak temperature 140°C) as the first layer on the outer packaging material side is extruded with a thickness of 30 μm, to obtain an adhesive film (total thickness 80 μm) formed by laminating in sequence the first layer (r-PP layer, thickness 30 μm) / polypropylene layer (CPP layer, thickness 30 μm) / second layer (r-PPa layer, thickness 20 μm).

[0193] Example 8

[0194] Using multi-layer air-cooled blow molding, a polypropylene film (PP layer) as the polypropylene layer (melt peak temperature 160 °C, thickness 80 μm), a maleic anhydride-modified polypropylene as the second layer on the metal terminal side (r-PPa layer (maleic anhydride-modified random polypropylene layer), melt peak temperature 140 °C, thickness 37.5 μm), and a maleic anhydride-modified polypropylene as the first layer on the outer packaging material side (r-PPa layer (maleic anhydride-modified random polypropylene layer), melt peak temperature 140 °C, thickness 37.5 μm) are molded to obtain an adhesive film for metal terminals (total thickness 150 μm) formed by laminating a first polyolefin layer (PPa layer thickness 37.5 μm) / substrate (PP layer thickness 80 μm) / second polyolefin layer (PPa layer thickness 37.5 μm) in sequence.

[0195] Example 9

[0196] A polypropylene film (CPP layer (unstretched homopolypropylene layer), melt peak temperature 160 °C, thickness 80 μm) as the polypropylene layer is made into an adhesive film (total thickness 80 μm). The island ratio of the sea-island structure is adjusted by the addition amount of polyethylene in the polypropylene layer.

[0197] Example 10

[0198] Using an extruder and a T-die casting device, on one surface of a polypropylene film (CPP layer (unstretched homopolypropylene layer), melt peak temperature 160 °C, thickness 80 μm) as the polypropylene layer, maleic anhydride-modified polypropylene (r-PPa layer (maleic anhydride-modified random polypropylene layer), melt peak temperature 140 °C) is extruded with a thickness of 60 μm, and on the other surface, polypropylene (h-PP layer (homopolypropylene layer), melt peak temperature 140 °C) is extruded with a thickness of 60 μm as the first layer on the outer packaging material side, to obtain an adhesive film (total thickness 200 μm) formed by laminating a first layer (h-PP layer, thickness 60 μm) / polypropylene layer (CPP layer, thickness 80 μm) / second layer (r-PPa layer, thickness 60 μm) in sequence.

[0199] Example 11

[0200] Using an extruder and a T-die casting device, on one side of a polypropylene film (CPP layer (unstretched homopolypropylene layer), melting peak temperature 160 °C, thickness 80 μm) as the polypropylene layer, maleic anhydride-modified polypropylene (h-PPa layer (maleic anhydride-modified homopolypropylene layer), melting peak temperature 160 °C) as the second layer on the metal terminal side is extruded with a thickness of 60 μm. On the other side, polypropylene (r-PP layer (random polypropylene layer), melting peak temperature 140 °C) as the first layer on the outer packaging material side is extruded with a thickness of 60 μm, obtaining an adhesive film (total thickness 200 μm) formed by laminating the first layer (r-PP layer, thickness 60 μm) / polypropylene layer (CPP layer, thickness 80 μm) / second layer (h-PPa layer, thickness 60 μm) in sequence.

[0201] Example 12

[0202] Using an extruder and a T-die casting device, on one side of a polypropylene film (CPP layer (unstretched random polypropylene layer), melting peak temperature 140 °C, thickness 80 μm) as the polypropylene layer, maleic anhydride-modified polypropylene (r-PPa layer (maleic anhydride-modified random polypropylene layer), melting peak temperature 140 °C) as the second layer on the metal terminal side is extruded with a thickness of 60 μm. On the other side, polypropylene (h-PP layer (homopolypropylene layer), melting peak temperature 160 °C) as the first layer on the outer packaging material side is extruded with a thickness of 60 μm, obtaining an adhesive film (total thickness 200 μm) formed by laminating the first layer (h-PP layer, thickness 60 μm) / polypropylene layer (CPP layer, thickness 80 μm) / second layer (r-PPa layer, thickness 60 μm) in sequence.

[0203] Example 13

[0204] Using an extruder and a T-die casting device, on one side of a polypropylene film (CPP layer (unstretched random polypropylene layer), melting peak temperature 140 °C, thickness 80 μm) as the polypropylene layer, maleic anhydride-modified polypropylene (h-PPa layer (maleic anhydride-modified homopolypropylene layer), melting peak temperature 160 °C) as the second layer on the metal terminal side is extruded with a thickness of 60 μm. On the other side, polypropylene (r-PP layer (random polypropylene layer), melting peak temperature 140 °C) as the first layer on the outer packaging material side is extruded with a thickness of 60 μm, obtaining an adhesive film (total thickness 200 μm) formed by laminating the first layer (r-PP layer, thickness 60 μm) / polypropylene layer (CPP layer, thickness 80 μm) / second layer (h-PPa layer, thickness 60 μm) in sequence.

[0205] Example 14

[0206] Using multi-layer air-cooled blow molding, a polypropylene film (h-PP layer, melting peak temperature 160 °C, thickness 30 μm) as the polypropylene layer, maleic anhydride-modified polypropylene (r-PPa layer (maleic anhydride-modified random polypropylene layer), melting peak temperature 140 °C, thickness 50 μm) as the second layer on the metal terminal side, and polypropylene (r-PP layer (random polypropylene layer, melting peak temperature 140 °C, thickness 20 μm)) as the first layer on the outer packaging material side are molded to obtain an adhesive film for metal terminals (total thickness 100 μm) formed by laminating a first polyolefin layer (PP layer thickness 20 μm) / substrate (PP layer thickness 30 μm) / second polyolefin layer (PPa layer thickness 50 μm) in sequence.

[0207] Comparative Example 1

[0208] Using multi-layer air-cooled blow molding, a polypropylene film (PP layer), melting peak temperature 160 °C, thickness 20 μm) as the polypropylene layer, maleic anhydride-modified polypropylene (r-PPa layer (maleic anhydride-modified random polypropylene layer), melting peak temperature 140 °C, thickness 40 μm), polypropylene (r-PP layer (random polypropylene layer, melting peak temperature 140 °C, thickness 35 μm), polypropylene (r-PP layer (random polypropylene layer, melting peak temperature 140 °C, thickness 20 μm)) as the first layer on the outer packaging material side, and polypropylene (r-PP layer (random polypropylene layer, melting peak temperature 140 °C, thickness 35 μm)) are molded to obtain an adhesive film (total thickness 150 μm) formed by laminating a PP layer (thickness 20 μm) / PP layer (thickness 35 μm) / PP layer (thickness 20 μm) / PP layer (thickness 35 μm) / PPa layer (thickness 40 μm) in sequence.

[0209] Comparative Example 2

[0210] A polypropylene film (CPP layer (unstretched homopolypropylene layer), homopolypropylene, melting peak temperature 160 °C, thickness 80 μm) as the polypropylene layer is made into an adhesive film (total thickness 80 μm). The island ratio of the sea-island structure is adjusted by the addition amount of polyethylene in the polypropylene layer.

[0211] Comparative Example 3

[0212] Using an extruder and a T-die casting device, on a polypropylene film as the polypropylene layer (PP layer (polypropylene layer), polypropylene, melting peak temperature 160°C, thickness 70 μm), maleic anhydride-modified polypropylene as the second layer on the metal terminal side is extruded at a thickness of 70 μm (r-PPa layer (maleic anhydride-modified random polypropylene layer), melting peak temperature 140°C). On the other side, polypropylene as the first layer on the outer packaging material side is co-extruded at a thickness of 60 μm (r-PP layer (random polypropylene layer), melting peak temperature 140°C), to obtain an adhesive film (total thickness 200 μm) formed by laminating the first layer (r-PP layer (random polypropylene layer), thickness 60 μm) / polypropylene layer (PP layer, thickness 70 μm) / second layer (r-PPa layer, thickness 70 μm) in sequence.

[0213] Comparative Example 4

[0214] Using an extruder and a T-die casting device, on a polypropylene film as the polypropylene layer (PP layer (isotactic polypropylene layer), polypropylene, melting peak temperature 160°C, thickness 60 μm), maleic anhydride-modified polypropylene as the second layer on the metal terminal side is extruded at a thickness of 50 μm (r-PPa layer (maleic anhydride-modified random polypropylene layer), melting peak temperature 140°C). On the other side, polypropylene as the first layer on the outer packaging material side is extruded at a thickness of 40 μm (r-PP layer (random polypropylene layer), melting peak temperature 140°C), to obtain an adhesive film (total thickness 150 μm) formed by laminating the first layer (r-PP layer (random polypropylene layer), thickness 40 μm) / polypropylene layer (PP layer, thickness 60 μm) / second layer (r-PPa layer, thickness 50 μm) in sequence.

[0215] <Measurement of the island portion ratio of the sea-island structure of the polypropylene layer>

[0216] The island portion ratio of the sea-island structure of the polypropylene layer of the adhesive film is measured by the following method. When the adhesive film is composed of a single layer of the polypropylene layer, the single-layer polypropylene layer is taken as the measurement object. In addition, when the adhesive film is composed of multiple layers, the polypropylene layer that does not form the surface of the adhesive film is taken as the measurement object, and the island portion ratio of the polypropylene layer with the smallest island portion ratio (specifically, the h-CPP layer or r-CPP layer in Examples 1 to 14 and Comparative Examples 2 to 4, and the h-PP layer in Comparative Example 1) is shown in Table 1.

[0217] Embed the adhesive film in a thermosetting epoxy resin and cure it. Using a commercially available rotary microtome (UC6 manufactured by LEICA) and a diamond knife, prepare a cross-section in the target direction (a cross-section parallel to the TD and in the thickness direction). At this time, use a cryo-ultramicrotome with liquid nitrogen to prepare the cross-section at -70 °C. Stain each embedded resin with ruthenium tetroxide for 12 hours. When staining, the polypropylene expands, so trim the expanded part with a microtome and cut it in the direction of the MD from 100 nm in increments of 300 nm. When cutting a total of about 1 μm to 2 μm, observe the cross-section where the polypropylene layer is exposed as follows. For the stained cross-section, observe it using a field emission scanning electron microscope (S-4800 TYPE1 manufactured by Hitachi High-Technologies Corporation, measurement conditions: 3 kV 20 mA High WD6 mm detector (Upper)) to obtain an image (magnification: 10,000 times). Then, use image processing software (Image Analysis Software WinROOF (Ver7.4) manufactured by Mitani Corporation) that can binarize the image. For this image, binarize the island part and the sea part of the sea-island structure and calculate the ratio of the total area of the island part (total area of the island part / area of the measurement range of the image). The results are shown in Table 1. In addition, in this measurement, since the island part is stained more than the sea part, the island part looks brighter than the sea part.

[0218] [Image Processing Conditions]

[0219] Image processing is performed using the image analysis software ImageJ. Specifically, obtain the SEM image in the form of a digital file of a grayscale image (JPEG) and process it according to the following binarization processing steps and parameters. Output the pixels with a tone (bright) above the threshold as 1 and the pixels with a tone (dark) less than the threshold as 0, and respectively define them as the island part and the sea part.

[0220] <Binarization Processing>

[0221] 1. Remove spike noise (Despeckle)

[0222] 2. Remove the outline of the island part (Remove Outliers radius = 4 threshold = 1 which = Bright)

[0223] 3. Remove the outline of the sea part (Remove Outliers radius = 4 threshold = 1 which = Dark)

[0224] 4. Remove spike noise (Despeckle)

[0225] 5. Gaussian blur in the X-axis (short side of the sample) direction (threshold = 3 pixels)

[0226] 6. Contrast enhancement (saturated = 0.2)

[0227] 7. Removal of the outline of the island part (Remove Outliers radius = 4 threshold = 1 which = Bright)

[0228] 8. Removal of the outline of the sea part (Remove Outliers radius = 4 threshold = 1 which = Dark)

[0229] 9. Otsu binarization

[0230] <Measurement of the ratio of the soft segment component after heating the adhesive film>

[0231] The adhesive film was heated under the conditions of a temperature of 200 °C, a surface pressure of 0.25 MPa, and 16 seconds as a sample. Then, the ratio of the soft segment component after heating the adhesive film (the ratio of the soft segment component by the solid echo method using pulsed NMR) was measured by the following method.

[0232] The sample was introduced into a glass sample tube with a diameter of 10 mm, and the sample tube was set in a pulsed NMR device (the minispec mq20 manufactured by BRUKER). After maintaining at 440 °C for 5 minutes, a free induction decay curve of 1H spin - spin relaxation was obtained by the solid echo method at 40 °C. The number of scans in the solid echo method was set to 64 times. The obtained decay curve waveform was separated into three curves of three components derived from the hard segment component, the middle segment component, and the soft segment component. The waveform separation was performed using the analysis software "TD - NMRA (Version 4.3 Rev 0.8)" manufactured by BRUKER. The hard segment component was obtained by fitting with a Gaussian function, and the middle segment component and the soft segment component were obtained by fitting with an exponential function. The measurement points up to 0.6 msec of the relaxation curve were used in the analysis. The fitting was performed using the following formula.

[0233] Y = A1×exp(-(t / τ1) w1 ) + A2×exp(-(t / τ2) w2 ) + A3×exp(-(t / τ3) w3 )

[0234] Among them, w1 to w3 are Weber coefficients, w1 takes a value of 2, and w2 and w3 take values of 1. A1 is the component ratio of the hard segment component, A2 is the component ratio of the middle segment component, A3 is the component ratio of the soft segment component, τ1 represents the relaxation time of the hard segment component, τ2 represents the relaxation time of the middle segment component, τ3 represents the relaxation time of the soft segment component, and t is the time.

[0235] <Measurement of Heat of Fusion after Heating of Adhesive Film>

[0236] The adhesive film is heated under the conditions of a temperature of 200 °C, a surface pressure of 0.25 MPa, and 16 seconds. Subsequently, the heat of fusion is measured in accordance with the provisions of JIS K7122:2012. The measurement is performed using a differential scanning calorimeter (DSC, differential scanning calorimeter TA7000 manufactured by Hitachi High-Technologies Corporation). After holding the measurement sample at -50 °C for 15 minutes, it is heated from -50 °C to 210 °C at a heating rate of 10 °C / minute, and the heat of fusion ΔH (J / g) for the first time is measured. Then, it is held at 210 °C for 10 minutes. Next, it is cooled from 210 °C to -50 °C at a cooling rate of 10 °C / minute and held for 15 minutes. Furthermore, it is heated from -50 °C to 210 °C at a heating rate of 10 °C / minute, and the heat of fusion ΔH (J / g) for the second time is measured. Among them, the flow rate of nitrogen is set to 50 ml / minute. The value of the heat of fusion ΔH (J / g) measured for the first time through the above steps is used as the heat of fusion. The heat of fusion is the area enclosed by the baseline (the line formed by connecting the starting point and the ending point of the edge line from the bottom line to the bottom line) and the peak in the DSC curve.

[0237] <Measurement of Water Vapor Transmission Rate of Adhesive Film>

[0238] First, the following steps are used to prepare an outer packaging material for an electrical storage device (hereinafter, sometimes simply referred to as "outer packaging material"). As the base material layer, a biaxially stretched polyethylene terephthalate (PET) film (thickness 12 μm) and a stretched nylon (ONy) film (thickness 15 μm) are prepared. The PET film and the ONy film are bonded using a two-component polyurethane adhesive (a polyol compound and an aromatic isocyanate compound), and an aging treatment is performed. Thus, a base material layer (thickness 30 μm) is obtained, which is laminated in order from the outside as a PET film (thickness 12 μm) / adhesive layer (cured thickness 3 μm) / ONy film (thickness 15 μm). In addition, as the barrier layer, an aluminum foil (JIS H4160:1994 A8021H - O (thickness 40 μm)) is prepared. Then, the surface on the ONy film side of the base material layer and the barrier layer are bonded using a two-component polyurethane adhesive (a polyol compound and an aromatic isocyanate compound), and an aging treatment is performed. Thus, an outer packaging material for an electrical storage device (total thickness 73 μm) is obtained, which is laminated in order as a base material layer (thickness 30 μm) / adhesive layer (cured thickness 3 μm) / barrier layer (thickness 40 μm).

[0239] Next, as shown in the Figure 9 schematic diagram, the obtained outer packaging material 3 is cut into a square with a longitudinal (MD) dimension of 120 mm and a transverse (TD) dimension of 120 mm ( Figure 9(a)). In addition, prepare two rectangular pieces of the adhesive film 1 cut longitudinally (MD) to 120 mm and transversely (TD) to 10 mm, and two rectangular pieces cut longitudinally (MD) to 100 mm and transversely (TD) to 10 mm. On the barrier layer side of the outer packaging material 3, along the periphery of the outer packaging material 3, the adhesive films with the same longitudinal length are arranged opposite to each other ( Figure 9 (b)). At this time, make the second layer side of the adhesive film the barrier layer side of the outer packaging material 3. Then, place a polytetrafluoroethylene film (PTFE film, thickness 100 μm) on the adhesive film of the laminate (cover the surface of the adhesive film with the PTFE film), and place it on a press heated to 200 °C in the state of silicon wafer / PTFE / this laminate / PTFE / silicone sponge sheet, and leave it still for 16 seconds under the condition of a pressure of 0.25 MPa to thermally bond the adhesive film to the outer packaging material 3. Naturally cool the thermally bonded laminate to 25 °C and peel off the PTFE film from the laminate. This heat treatment assumes the heat of the physical properties after the adhesive film is arranged between the outer packaging material for the electrical storage device and the metal terminal and is thermally bonded. Next, make the adhesive film the inner side and fold the outer packaging material 3 in half longitudinally ( Figure 9 (c)). Two pieces of the adhesive film for the metal terminal with a longitudinal (MD) length of 120 mm are arranged overlapping between the outer packaging materials 3 along the long side to be heat-sealed described later, and two pieces of the adhesive film for the metal terminal with a longitudinal (MD) length of 100 mm are arranged folded in half between the outer packaging materials 3 along the short side to be heat-sealed described later. The peripheral part of the outer packaging material 3 becomes a laminate formed by laminating the outer packaging material / adhesive film / adhesive film / outer packaging material in sequence ( Figure 9 (c)).

[0240] Next, use a heat-sealing bar (stainless steel plate) to thermally bond the layers of the laminate at the positions of the long side and the short side of the laminate to form a bag shape with one short side not thermally bonded ( Figure 9 (c)). The heat-sealing conditions are: for the long side, use a heat-sealing bar with a width of 7 mm and heat-seal once under the conditions of a temperature of 190 °C, a surface pressure of 0.5 MPa, and 1.5 seconds ( Figure 9 (s1) of (c)). In addition, for the short side, use a heat-sealing bar with a width of 7 mm and heat-seal once under the conditions of a temperature of 190 °C, a surface pressure of 0.5 MPa, and 1.5 seconds ( Figure 9 (s2) of (c)). Dry it in a drying room for 1 day. Then, inject about 3.0 g of a liquid with ethylene carbonate:diethyl carbonate:dimethyl carbonate = 1:1:1 (volume ratio) (moisture content 0%) from the position of the short side not thermally bonded ( Figure 9 (d)), and heat-seal the short side not thermally bonded in the same way as the above-mentioned short side ( Figure 9 (s3) of (e)) to form a sealed bag ( Figure 9(e)). After leaving the sealed bag to stand for 30 days in an environment of 65°C and 90% relative humidity, in a drying chamber, the moisture content of the liquid taken out from the sealed bag was measured by the Karl Fischer method to obtain the moisture content (ppm). From the obtained moisture content, the amount of electrolyte input (g), the permeation distance (mm), the permeation cross-sectional area (m 2 ), and the number of storage days (days), the water vapor transmission rate (g·mm / (m 2 ·day)) was calculated.

[0241] Water vapor transmission rate (g·mm / (m 2 ·day)) = [Obtained moisture content (ppm) × Input electrolyte (g) × Permeation distance (mm)] / [Permeation cross-sectional area (m 2 ) × Number of storage days (days)]

[0242] · Obtained moisture content (ppm): Obtained by the Karl Fischer method.

[0243] · Input electrolyte (g): 3.0 g

[0244] · Permeation distance (mm): Sealing part width 7 mm

[0245] · Permeation cross-sectional area (m 2 ): Residual thickness (μm) × Inner circumference of the sealing part (mm)

[0246] · Number of storage days (days): 30 days

[0247] <Measurement of the adhesion strength between the adhesive film and the metal terminal>

[0248] The adhesive strength between the adhesive film and the metal terminal was measured through the following steps. The results are shown in Table 1. The adhesive strength of the adhesive film to the metal terminal was measured by the following method. The results are shown in Table 1. As the metal terminal, aluminum (JIS H4160:1994 A8079H-O) with a length of 50 mm, a width of 22.5 mm, and a thickness of 400 μm was prepared. In addition, each metal terminal obtained in the examples and comparative examples was cut into a length of 45 mm and a width of 10 mm with the adhesive film. Next, the metal terminal with the adhesive film was placed on the metal terminal to obtain a laminate of the metal terminal / adhesive film. At this time, the laminate was made such that the longitudinal and transverse directions of the metal terminal were aligned with the length and width directions of the metal terminal with the adhesive film, respectively, and the centers of the metal terminal and the metal terminal with the adhesive film were aligned. In addition, the second layer of the metal terminal with the adhesive film was arranged on the metal terminal side. Next, while a polytetrafluoroethylene film (PTFE film, thickness 100 μm) was placed on the metal terminal with the adhesive film of the laminate (covering the surface of the metal terminal with the adhesive film), it was placed on a press heated to 200 °C (the metal terminal was on the heating plate side), and at the same time, a silicone sponge sheet was placed, and it was left standing for 16 seconds at a pressure of 0.25 MPa to thermally bond the adhesive film to the metal terminal. The heat-bonded laminate (pre-sealed tab) was naturally cooled to 25 °C. Next, in an environment of 25 °C, the metal terminal with the adhesive film was peeled off from the metal terminal using a Tensilon universal material testing machine (RTG-1210 manufactured by A&D Company). Specifically, in the center part of the obtained pre-sealed tab, a cut was made along the transverse direction of the metal terminal, and the cut part was bent several times, whereby only the metal terminal was broken by metal fatigue. Next, as Figure 12 shown in the schematic diagram, with the cut part of the metal terminal (the central part of the pre-sealed tab 20) as the boundary, for one side of the longitudinal direction (x direction, MD) of the metal terminal, the metal terminal protruding from the adhesive film was cut off. Figure 12 The double-dashed line part of Figure 13 is the part where the metal terminal was cut off. Next, as Figure 13 shown, a tape 21 was attached to the side of the pre-sealed tab where the metal terminal 2 was cut off. A jig 22 for fixing the pre-sealed tab was installed on the other side of the pre-sealed tab. The tape 21 and the jig 22 were respectively installed on the chuck 23 of the Tensilon universal material testing machine, and by stretching the distance between the chucks in the 180° direction, the metal terminal with the adhesive film was peeled off from the metal terminal. The maximum strength at the time of peeling was taken as the adhesion strength to the metal terminal (N / 15 mm). The peeling speed was set to 50 mm / minute, the peeling angle was set to 180°, the distance between the chucks was set to 30 mm, and the average value of 3 measurements was taken. The results are shown in Table 1. Among them, the treatment of standing for 16 seconds in a heating and pressurizing environment at a temperature of 200 °C and a surface pressure of 0.25 MPa is a treatment assuming the heat and pressure applied in the above-mentioned pre-bonding process and main bonding process.

[0249] <Measurement of Adhesion Strength between Adhesive Film and Exterior Material>

[0250] The adhesion strength between the exterior material of the adhesive film and the metal terminal was measured through the following steps. The results are shown in Table 1.

[0251] (Fabrication of Exterior Material)

[0252] First, an exterior material for a storage device (hereinafter sometimes simply referred to as "exterior material") was fabricated through the following steps. A base material layer (30 μm thick) composed of a polyethylene terephthalate film (12 μm thick) / adhesive layer (3 μm thick) / nylon film (15 μm thick) was laminated on an aluminum alloy foil (40 μm thick) by dry lamination, and a heat-sealable resin layer was co-extrusion laminated on the other side. Specifically, a two-component polyurethane adhesive (polyol compound and aromatic isocyanate compound) was coated on the nylon film to form an adhesive layer (3 μm thick) on the nylon film. Then, the adhesive layer and the polyethylene terephthalate film were laminated on the nylon film to fabricate the base material layer. Then, a two-component polyurethane adhesive (polyol compound and aromatic isocyanate compound) was coated on one surface of the barrier layer composed of aluminum alloy foil to form an adhesive layer (3 μm thick) on the aluminum alloy foil. Then, after laminating the adhesive layer and the base material layer with the nylon film side as the adhesive surface on the aluminum alloy foil, an aging treatment was performed to fabricate a laminate of the base material layer / adhesive layer / barrier layer. Then, on the barrier layer of the laminate, a bonding layer (40 μm thick, disposed on the metal layer side) composed of maleic anhydride-modified polypropylene resin and a heat-sealable resin layer (40 μm thick, innermost layer) composed of random polypropylene resin were co-extruded, whereby the bonding layer / heat-sealable resin layer was laminated on the barrier layer, and an exterior material for a storage device in which the base material layer, adhesive layer, barrier layer, bonding layer, and heat-sealable resin layer were laminated in sequence was obtained.

[0253] Next, as the metal terminal 2, an aluminum foil with MD 25 mm, TD 22.5 mm, and a thickness of 400 μm (JIS H4160: 1994 A8079H - O) was prepared. In addition, each adhesive film 1 obtained in the examples and comparative examples was cut into MD 25 mm and TD 20 mm. Next, as shown in the schematic diagram of Figure 10 a metal terminal was sandwiched between two adhesive films to obtain a laminate of adhesive film / metal terminal / adhesive film. At this time, the MD and TD of the metal terminal were aligned with the length direction and width direction of the adhesive film, respectively, and the metal terminal was aligned with the center of the adhesive film for lamination (refer to Figure 10(a)). Further, the second layer of the adhesive film for metal terminals is disposed on the metal terminal side. Next, in a state where the laminate is sandwiched between two polytetrafluoroethylene films (PTFE films, thickness 100 μm), it is heated under the conditions of a temperature of 200 °C, a surface pressure of 0.25 MPa, and 16 seconds to thermally bond the adhesive film to the metal terminal, thereby fabricating a metal terminal with an adhesive film (refer to Figure 10 of (b)). At this time, as shown in the schematic diagram of Figure 10 , by sandwiching the metal terminal with the adhesive film, a portion is formed where the periphery of the metal terminal is covered with the adhesive film and the two adhesive films are thermally bonded to each other. Next, the outer packaging material is cut into dimensions of TD 60 mm and MD 200 mm. As shown in the schematic diagram of Figure 11 , the outer packaging materials are opposed to each other with the heat-sealable resin layer on the inside, and the obtained laminate is sandwiched between the opposed heat-sealable resin layers (refer to Figure 11 of (a)). At this time, the outer packaging materials are laminated such that MD and TD thereof are aligned with the width direction and the length direction of the laminate, respectively. In this state, using a heat-sealing tester, heat sealing is performed under the conditions of a width of 7 mm ( Figure 11 the y-axis direction in (b) is 7 mm), a temperature of 200 °C, a surface pressure of 3.0 MPa, and 1.5 seconds (refer to the hatched area S in Figure 11 of (b)), and it is naturally cooled to 25 °C to obtain a laminate in which the outer packaging material and the adhesive film are thermally bonded (refer to Figure 11 of (b)). Next, the central portion in the short-side direction of the obtained laminate is cut into a width of 15 mm (the cutting position refers to the double-dot chain line in Figure 11 of (b)). Next, in an environment of 25 °C, the adhesive film and the heat-sealable resin layer of the outer packaging material are peeled using a Tensilon universal material testing machine (RTG-1210 manufactured by A&D Company). The maximum strength at the time of peeling is defined as the peeling strength (N / 15 mm) with respect to the outer packaging material. The peeling speed is set to 20 mm / minute, the peeling angle is set to 180°, the distance between the chucks is set to 30 mm, and the average value of three measurements is taken.

[0254] [Table 1]

[0255]

[0256] In Table 1, the values in the laminate structure of the adhesive film indicate the thickness (μm) of each layer.

[0257] As described above, the present invention provides an invention in the manner described below.

[0258] Item 1. An adhesive film for a metal terminal, which is present between a metal terminal electrically connected to an electrode of an electric storage device element and an exterior material for an electric storage device that encapsulates the electric storage device element, wherein,

[0259] the adhesive film for the metal terminal contains at least a polypropylene layer,

[0260] in a cross-sectional image in the thickness direction of a direction parallel to TD of the polypropylene layer obtained using a scanning electron microscope, a sea-island structure is observed,

[0261] the island portion ratio of the sea-island structure of the polypropylene layer is 20% or less.

[0262] Item 2. The adhesive film for a metal terminal according to Item 1, wherein the adhesive film for the metal terminal is composed of a single layer of the polypropylene layer.

[0263] Item 3. The adhesive film for a metal terminal according to Item 1, wherein the adhesive film for the metal terminal is composed of multiple layers,

[0264] the polypropylene layer is not a layer that constitutes the surface of the adhesive film for the metal terminal.

[0265] Item 4. The adhesive film for a metal terminal according to Item 3, wherein the ratio of the thickness of the polypropylene layer to the thickness of the adhesive film for the metal terminal is 0.20 or more.

[0266] Item 5. The adhesive film for a metal terminal according to any one of Items 1 to 4, wherein the polypropylene layer contains modified polypropylene.

[0267] Item 6. The adhesive film for a metal terminal according to any one of Items 1 to 5, wherein after heating the adhesive film for the metal terminal under the conditions of a temperature of 200 °C, a surface pressure of 0.25 Pa, and 16 seconds, in an environment at a temperature of 40 °C, the ratio of the soft segment component of the adhesive film for the metal terminal measured by the solid echo method using pulsed NMR is 20% or less.

[0268] Item 7. The adhesive film for a metal terminal according to any one of Items 1 to 6, wherein the heat of fusion measured after heating the adhesive film for the metal terminal under the conditions of a temperature of 200 °C, a surface pressure of 0.25 Pa, and 16 seconds is 50 J / g or more.

[0269] Item 8. The adhesive film for a metal terminal according to any one of Items 1 to 7, wherein the water vapor transmission rate of the adhesive film for the metal terminal is 5.10 g·mm / (m 2 ·day) or less.

[0270] Item 9. A method for manufacturing an adhesive film for a metal terminal, the adhesive film for a metal terminal being present between a metal terminal electrically connected to an electrode of an electrical storage device element and an exterior material for an electrical storage device that encapsulates the electrical storage device element,

[0271] The adhesive film for a metal terminal includes at least a polypropylene layer,

[0272] In a cross-sectional image of a cross-section in the thickness direction in the direction parallel to TD of the polypropylene layer obtained using a scanning electron microscope, a sea-island structure is observed,

[0273] The island portion ratio of the sea-island structure of the polypropylene layer is 20% or less.

[0274] Item 10. A metal terminal with an adhesive film for a metal terminal, which is formed by mounting the adhesive film for a metal terminal according to any one of Items 1 to 8 on a metal terminal.

[0275] Item 11. An electrical storage device, comprising: an electrical storage device element having at least a positive electrode, a negative electrode, and an electrolyte; an exterior material for an electrical storage device that encapsulates the electrical storage device element; and the metal terminals that are electrically connected to the positive electrode and the negative electrode respectively and protrude to the outside of the exterior material for an electrical storage device,

[0276] Between the metal terminal and the exterior material for an electrical storage device, there is an adhesive film for a metal terminal according to any one of Items 1 to 8.

[0277] Item 12. A method for manufacturing an electrical storage device, the electrical storage device comprising: an electrical storage device element having at least a positive electrode, a negative electrode, and an electrolyte; the exterior material for an electrical storage device that encapsulates the electrical storage device element; and the metal terminals that are electrically connected to the positive electrode and the negative electrode respectively and protrude to the outside of the exterior material for an electrical storage device,

[0278] The method for manufacturing the electrical storage device includes:

[0279] A step of making an adhesive film for a metal terminal according to any one of Items 1 to 8 exist between the metal terminal and the exterior material for an electrical storage device, and encapsulating the electrical storage device element with the exterior material for an electrical storage device.

[0280] Item 13. An exterior material for an electrical storage device for an electrical storage device, the electrical storage device comprising: an electrical storage device element having at least a positive electrode, a negative electrode, and an electrolyte; an exterior material for an electrical storage device that encapsulates the electrical storage device element; and the metal terminals that are electrically connected to the positive electrode and the negative electrode respectively and protrude to the outside of the exterior material for an electrical storage device, between the metal terminal and the exterior material for an electrical storage device, there is an adhesive film for a metal terminal,

[0281] The adhesive film for metal terminals is the adhesive film for metal terminals described in any one of Items 1 to 8.

[0282] The exterior material for the electrical storage device is composed of a laminate having at least a base material layer, a barrier layer, and a heat-sealable resin layer.

[0283] Item 14. A kit, comprising: an exterior material for an electrical storage device for an electrical storage device, and an adhesive film for metal terminals described in any one of Items 1 to 8.

[0284] The electrical storage device includes: an electrical storage device element having at least a positive electrode, a negative electrode, and an electrolyte; an exterior material for the electrical storage device that encapsulates the electrical storage device element; and the metal terminals that are electrically connected to the positive electrode and the negative electrode respectively and protrude to the outside of the exterior material for the electrical storage device.

[0285] In use, it is used in such a manner that the adhesive film for metal terminals is present between the metal terminals and the exterior material for the electrical storage device.

[0286] Symbol Explanation

[0287] 1 Adhesive film for metal terminals

[0288] 2 Metal terminals

[0289] 3 Exterior material for electrical storage device

[0290] 3a Peripheral portion of the exterior material for the electrical storage device

[0291] 4 Electrical storage device element

[0292] 10 Electrical storage device

[0293] 11 Polypropylene layer

[0294] 12a First layer

[0295] 12b Second layer

[0296] 12c Third layer

[0297] 31 Base material layer

[0298] 32 Adhesive layer

[0299] 33 Barrier layer

[0300] 34 Bonding layer

[0301] 35 Heat-sealable resin layer.

Claims

1. An adhesive film for a metal terminal, which is present between a metal terminal electrically connected to an electrode of an electrical storage device element and an exterior material for an electrical storage device that encapsulates the electrical storage device element, wherein the adhesive film for a metal terminal is characterized in that: The adhesive film for a metal terminal contains at least a polypropylene layer, In a cross-sectional image obtained by a scanning electron microscope of a cross-section in the direction parallel to TD and in the thickness direction of the polypropylene layer, a sea-island structure is observed, The island portion ratio of the sea-island structure of the polypropylene layer is 20% or less.

2. The adhesive film for a metal terminal according to claim 1, wherein: The adhesive film for a metal terminal is composed of a single layer of the polypropylene layer.

3. The adhesive film for a metal terminal according to claim 1, wherein: The adhesive film for a metal terminal is composed of multiple layers, The polypropylene layer is not a layer that constitutes the surface of the adhesive film for a metal terminal.

4. The adhesive film for a metal terminal according to claim 3, wherein: The ratio of the thickness of the polypropylene layer to the thickness of the adhesive film for a metal terminal is 0.20 or more.

5. The adhesive film for a metal terminal according to any one of claims 1 to 4, wherein: The polypropylene layer contains modified polypropylene.

6. The adhesive film for a metal terminal according to any one of claims 1 to 4, wherein: After the adhesive film for a metal terminal is heated under the conditions of a temperature of 200 °C, a surface pressure of 0.25 Pa, and 16 seconds, in an environment of a temperature of 40 °C, the ratio of the soft segment component measured by the solid echo method using pulsed NMR of the adhesive film for a metal terminal is 20% or less.

7. The adhesive film for a metal terminal according to any one of claims 1 to 4, wherein: The heat of fusion measured after the adhesive film for a metal terminal is heated under the conditions of a temperature of 200 °C, a surface pressure of 0.25 Pa, and 16 seconds is 50 J / g or more.

8. The adhesive film for a metal terminal according to any one of claims 1 to 4, wherein: The water vapor transmission rate of the adhesive film for metal terminals is 5.10 g·mm / (m 2 ·day) or less.

9. A method for manufacturing an adhesive film for a metal terminal, the adhesive film for a metal terminal being present between a metal terminal electrically connected to an electrode of an electrical storage device element and an exterior material for an electrical storage device that encapsulates the electrical storage device element, wherein the manufacturing method is characterized in that: The adhesive film for a metal terminal contains at least a polypropylene layer, In a cross-sectional image obtained by a scanning electron microscope of a cross-section in the direction parallel to TD and in the thickness direction of the polypropylene layer, a sea-island structure is observed, The island portion ratio of the sea-island structure of the polypropylene layer is 20% or less.

10. A metal terminal with an adhesive film for a metal terminal, characterized in that: It is formed by mounting the adhesive film for a metal terminal according to any one of claims 1 to 4 on a metal terminal.

11. An electrical storage device, characterized in that: Comprising: An electrical storage device element having at least a positive electrode, a negative electrode, and an electrolyte; an exterior material for an electrical storage device that encapsulates the electrical storage device element; and the metal terminals that are electrically connected to the positive electrode and the negative electrode respectively and protrude to the outside of the exterior material for the electrical storage device Between the metal terminal and the exterior material for the electrical storage device, there is the adhesive film for the metal terminal according to any one of claims 1 to 4.

12. A method for manufacturing an electrical storage device, characterized in that: The electrical storage device includes: an electrical storage device element having at least a positive electrode, a negative electrode, and an electrolyte; the exterior material for the electrical storage device that encapsulates the electrical storage device element; and the metal terminals that are electrically connected to the positive electrode and the negative electrode respectively and protrude to the outside of the exterior material for the electrical storage device The method for manufacturing the electrical storage device includes: a step of disposing the adhesive film for the metal terminal according to any one of claims 1 to 4 between the metal terminal and the exterior material for the electrical storage device, and encapsulating the electrical storage device element with the exterior material for the electrical storage device.

13. An exterior material for an electrical storage device for an electrical storage device, characterized in that: The electrical storage device includes: an electrical storage device element having at least a positive electrode, a negative electrode, and an electrolyte; the exterior material for the electrical storage device that encapsulates the electrical storage device element; and the metal terminals that are electrically connected to the positive electrode and the negative electrode respectively and protrude to the outside of the exterior material for the electrical storage device. Between the metal terminal and the exterior material for the electrical storage device, there is an adhesive film for the metal terminal The adhesive film for the metal terminal is the adhesive film for the metal terminal according to any one of claims 1 to 4 The exterior material for the electrical storage device is composed of a laminate having at least a base material layer, a barrier layer, and a heat-sealable resin layer.

14. A kit, characterized in that: The kit includes an exterior material for an electrical storage device for an electrical storage device, and the adhesive film for the metal terminal according to any one of claims 1 to 4 The electrical storage device includes: an electrical storage device element having at least a positive electrode, a negative electrode, and an electrolyte; the exterior material for the electrical storage device that encapsulates the electrical storage device element; and the metal terminals that are electrically connected to the positive electrode and the negative electrode respectively and protrude to the outside of the exterior material for the electrical storage device When in use, it is used in such a manner that the adhesive film for the metal terminal is present between the metal terminal and the exterior material for the electrical storage device.

Images