Adhesive film for metal terminals and method for producing the same, metal terminal provided with adhesive film for metal terminals, outer package material for power storage devices, kit comprising outer package material for power storage devices and adhesive film for metal terminals, and power storage device and method for producing the same

Abstract

To provide an adhesive film for metal terminals with excellent adhesion to metal terminals.SOLUTION: The present invention provides an adhesive film 1 for metal terminals which is interposed between a metal terminal 2 electrically connected to an electrode of a power storage device element and an outer package material 3 for power storage devices for sealing the power storage device element. With respect to the adhesive film for metal terminals, a resin layer A forming at least a surface on one side contains acid-modified polyolefin, and the surface of the resin layer A has a crystallinity of 3 or more and 18 or less as measured under the conditions described below by using an X-ray diffractometer. (Measurement conditions) An angle of X-ray irradiation is 0.09° with respect to the surface (0°) of the resin layer A. A measurement range is from the surface to a depth of 5 μm of the resin layer A. A camera length of an X-ray detector is 500 mm, an X-ray wavelength is 0.92 Å, and an exposure time is 30 seconds.SELECTED DRAWING: Figure 1

Description

[Technical field]

[0001] The present disclosure relates to an adhesive film for metal terminals and a method for producing the same, a metal terminal with an adhesive film for metal terminals, an exterior material for an electricity storage device, a kit including an exterior material for an electricity storage device and an adhesive film for metal terminals, and an electricity storage device and a method for producing the same. [Background technology]

[0002] Conventionally, various types of electricity storage devices have been developed, and in all electricity storage devices, exterior materials for electricity storage devices are essential components for sealing electricity storage device elements such as electrodes and electrolytes. Conventionally, metal exterior materials for electricity storage devices have been widely used as exterior materials for electricity storage devices, but in recent years, with the increasing performance of electric vehicles, hybrid electric vehicles, personal computers, cameras, mobile phones, etc., electricity storage devices are required to have a variety of shapes and are required to be thin and lightweight. However, conventionally widely used metal exterior materials for electricity storage devices have the disadvantages that it is difficult to keep up with the diversification of shapes and there is also a limit to the weight reduction.

[0003] In view of this, in recent years, a laminate sheet in which a base layer / adhesive layer / barrier layer / thermal adhesive resin layer are laminated in this order has been proposed as an exterior material for an electricity storage device that can be easily processed into various shapes and can realize a thinner and lighter weight. When such an exterior material for an electricity storage device in the form of a laminate film is used, the periphery of the exterior material for an electricity storage device is heat-sealed and thermally fused with heat sealing in a state in which the thermal adhesive resin layers positioned in the innermost layers of the exterior material for an electricity storage device face each other, thereby sealing the electricity storage device element with the exterior material for an electricity storage device.

[0004] A metal terminal protrudes from the heat-sealed portion of the exterior material for an electricity storage device, and the electricity storage device element sealed with the exterior material for an electricity storage device is electrically connected to the outside by the metal terminal electrically connected to the electrode of the electricity storage device element. That is, among the heat-sealed portions of the exterior material for an electricity storage device, the portion where the metal terminal is present is heat-sealed in a state where the metal terminal is sandwiched between the heat-sealable resin layer. Since the metal terminal and the heat-sealable resin layer are made of different materials, adhesion is likely to decrease at the interface between the metal terminal and the heat-sealable resin layer.

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

[0006] [Patent Document 1] JP 2015-79638 A Summary of the Invention [Problem to be solved by the invention]

[0007] The main object of the present disclosure is to provide an adhesive film for metal terminal, which is interposed between a metal terminal electrically connected to an electrode of an electricity storage device element and an exterior material for an electricity storage device that seals the electricity storage device element, and which has excellent adhesion to the metal terminal. Further objects of the present disclosure are to provide a method for producing the adhesive film for metal terminal, a metal terminal with an adhesive film for metal terminal, an exterior material for an electricity storage device, a kit including an exterior material for an electricity storage device and the adhesive film for metal terminal, an electricity storage device, and a method for producing the electricity storage device. [Means for solving the problem]

[0008] The inventors of the present disclosure have conducted intensive studies to solve the above problems. As a result, they have found that, in an adhesive film for metal terminals interposed between a metal terminal electrically connected to an electrode of an electric storage device element and an exterior material for an electric storage device that seals the electric storage device element, a resin layer A forming at least one surface of the adhesive film for metal terminals contains an acid-modified polyolefin, and the crystallinity of the surface of the resin layer A measured under specified conditions using an X-ray diffraction device is 3 to 18. The adhesive film for metal terminals has excellent adhesion to the metal terminal on the surface of the resin layer A side. The present disclosure has been completed through further studies based on such findings.

[0009] That is, the present disclosure provides the inventions of the following aspects. An adhesive film for a metal terminal, which is interposed between a metal terminal electrically connected to an electrode of an electricity storage device element and an exterior material for an electricity storage device that encapsulates the electricity storage device element, The adhesive film for metal terminal comprises a resin layer A forming at least one surface thereof, the resin layer A containing an acid-modified polyolefin, The adhesive film for metal terminal, wherein the surface of the resin layer A has a crystallinity of 3 or more and 18 or less, as measured under the following conditions using an X-ray diffraction device. (Measurement conditions) The angle of X-ray irradiation is set to 0.09° with respect to the surface of the resin layer A (0°). The measurement range is from the surface of the resin layer A to a depth of 5 μm. The camera length of the X-ray detector is 500 mm, the X-ray wavelength is 0.92 Å, and the exposure time is 30 seconds. Effect of the Invention

[0010] According to the present disclosure, it is possible to provide an adhesive film for a metal terminal, which is interposed between a metal terminal electrically connected to an electrode of an electricity storage device element and an exterior material for an electricity storage device that seals the electricity storage device element, and which has excellent adhesion to the metal terminal. Furthermore, the present disclosure also aims to provide a method for manufacturing the adhesive film for a metal terminal, a metal terminal with an adhesive film for a metal terminal, an exterior material for an electricity storage device, a kit including an exterior material for an electricity storage device and an adhesive film for a metal terminal, and an electricity storage device and a method for manufacturing the same. [Brief description of the drawings]

[0011] [Figure 1] FIG. 2 is a schematic plan view of the electricity storage device of the present disclosure. [Diagram 2] 2 is a schematic cross-sectional view taken along line AA' in FIG. 1. [Diagram 3] 2 is a schematic cross-sectional view taken along line BB' in FIG. 1. [Figure 4] 1 is a schematic cross-sectional view of an adhesive film for metal terminals according to the present disclosure. [Diagram 5] 1 is a schematic cross-sectional view of an adhesive film for metal terminals according to the present disclosure. [Figure 6] 1 is a schematic cross-sectional view of an adhesive film for metal terminals according to the present disclosure. [Figure 7] 1 is a schematic cross-sectional view of an adhesive film for metal terminals according to the present disclosure. [Figure 8] 1 is a schematic cross-sectional view of an exterior material for an electricity storage device according to the present disclosure. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0012] The adhesive film for metal terminal of the present disclosure is an adhesive film for metal terminal interposed between a metal terminal electrically connected to an electrode of an electricity storage device element and an exterior material for an electricity storage device that encapsulates the electricity storage device element, characterized in that a resin layer A forming at least one surface of the adhesive film for metal terminal contains an acid-modified polyolefin, and further, the crystallinity of the resin layer A measured using an X-ray diffraction apparatus under the following conditions is 3 or more and 18 or less.

[0013] (Measurement conditions) The angle of X-ray irradiation is set to 0.09° with respect to the surface of the resin layer A (0°). The measurement range is from the surface of the resin layer A to a depth of 5 μm. The camera length of the X-ray detector is 500 mm, the X-ray wavelength is 0.92 Å, and the exposure time is 30 seconds.

[0014] Since the adhesive film for metal terminal of the present disclosure has such characteristics, it has excellent adhesion to metal terminals.

[0015] The electricity storage device of the present disclosure is also an electricity storage device comprising at least an electricity storage device element having a positive electrode, a negative electrode, and an electrolyte, an exterior material for an electricity storage device that seals the electricity storage device element, and metal terminals electrically connected to each of the positive electrode and the negative electrode and protruding outside the exterior material for an electricity storage device, and is characterized in that an adhesive film for metal terminals of the present disclosure is interposed between the metal terminals and the exterior material for an electricity storage device.

[0016] The adhesive film for metal terminal and its manufacturing method, and the electricity storage device and its manufacturing method according to the present disclosure will be described in detail below.

[0017] In this specification, the numerical range indicated by "~" means "more than or equal to" or "less than or equal to". For example, the expression "2-15 mm" means 2 mm or more and 15 mm or less. In the numerical ranges described in the present disclosure in stages, the upper limit or lower limit described in a certain numerical range may be replaced with the upper limit or lower limit of another numerical range described in stages. In addition, the upper limit and the upper limit, the upper limit and the lower limit, or the lower limit and the lower limit described separately may be combined to form a numerical range. In addition, in the numerical ranges described in the present disclosure, the upper limit or the lower limit described in a certain numerical range may be replaced with a value shown in the examples.

[0018] 1. Adhesive film for metal terminals The adhesive film for metal terminal of the present disclosure is interposed between a metal terminal electrically connected to an electrode of an electricity storage device element and an exterior material for an electricity storage device that seals the electricity storage device element. Specifically, as shown in, for example, Fig. 1 to Fig. 3, the adhesive film for metal terminal 1 of the present disclosure is interposed between a metal terminal 2 electrically connected to an electrode of an electricity storage device element 4 and an exterior material for an electricity storage device 3 that seals the electricity storage device element 4. The metal terminal 2 protrudes outside the exterior material for an electricity storage device 3, and is sandwiched by the exterior material for an electricity storage device 3 via the adhesive film for metal terminal 1 at a peripheral portion 3a of the heat-sealed exterior material for an electricity storage device 3.

[0019] In the present disclosure, the temporary adhesion step of the adhesive film for metal terminal to the metal terminal is performed, for example, under conditions of 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, while the main adhesion step is performed, for example, under conditions of 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. In addition, when the metal terminal with the adhesive film for metal terminal is interposed between the exterior material for the electricity storage device and heat-sealed, the heating temperature is usually in the range of about 180 to 210°C, the pressure is usually about 1.0 to 5.0 MPa, the time of about 1 to 5 seconds, and the number of times is about 1.

[0020] The adhesive film 1 for metal terminals of the present disclosure is provided to improve the adhesion between the metal terminal 2 and the exterior material 3 for an electricity storage device. By improving the adhesion between the metal terminal 2 and the exterior material 3 for an electricity storage device, the sealing property of the electricity storage device element 4 is improved. As described above, when the electricity storage device element 4 is heat-sealed, the electricity storage device element is sealed such that the metal terminal 2 electrically connected to the electrode of the electricity storage device element 4 protrudes to the outside of the exterior material 3 for an electricity storage device. At this time, the metal terminal 2 formed of metal and the heat-sealable resin layer 35 (a layer formed of a heat-sealable resin such as polyolefin) located in the innermost layer of the exterior material 3 for an electricity storage device are formed of different materials, so that if such an adhesive film is not used, the sealing property of the electricity storage device element is likely to be reduced at the interface between the metal terminal 2 and the heat-sealable resin layer 35.

[0021] [Resin layer A] The adhesive film 1 for metal terminal of the present disclosure includes at least a resin layer A. The resin layer A forms at least one surface of the adhesive film 1 for metal terminal and is the outermost layer. That is, the adhesive film 1 for metal terminal of the present disclosure includes at least one resin layer A, and at least one surface of the adhesive film 1 for metal terminal is formed by the resin layer A. As long as the effects of the present disclosure are achieved, the adhesive film 1 for metal terminal of the present disclosure may be a single layer as shown in FIG. 4 or may be a multilayer as shown in FIGS. 5 to 7.

[0022] When the adhesive film 1 for metal terminal of the present disclosure is a single layer, the adhesive film 1 for metal terminal is composed of a resin layer A, and the surface on the metal terminal side and the surface of the exterior material for an electrical storage device are formed by the resin layer A. In this case, the resin forming the surface on the exterior material for an electrical storage device side of the adhesive film 1 for metal terminal and the resin forming the surface on the metal terminal side are common resins (i.e., resins constituting the resin layer A). Note that the resin forming the surface on the exterior material for an electrical storage device side of the adhesive film 1 for metal terminal and the resin forming the surface on the metal terminal side being common means that, for example, 80% by mass or more of the components in these resins are the same, 90% by mass or more are the same, 95% by mass or more are the same, or 100% by mass are the same.

[0023] When the adhesive film for metal terminal 1 of the present disclosure is a multi-layer structure, at least one layer may be composed of the resin layer A. For example, as shown in FIG. 5, when the adhesive film for metal terminal 1 of the present disclosure has a two-layer structure, the adhesive film for metal terminal 1 is a laminate of a first resin layer 12a and a second resin layer 12b. As described later, in the present disclosure, among these layers, the first resin layer 12a is composed of the resin layer A. Even when the adhesive film for metal terminal 1 of the present disclosure is a multi-layer structure, the resin forming the surface on the exterior material side for an electricity storage device and the resin forming the surface on the metal terminal side may be the same resin.

[0024] 6, when the adhesive film for metal terminal 1 of the present disclosure has a three-layer structure, the adhesive film for metal terminal 1 is a laminate in which a first resin layer 12a, an intermediate layer 11, and a second resin layer 12b are laminated in this order. In the present disclosure, the first resin layer 12a forms the surface on the metal terminal side, and the second resin layer 12b forms the surface on the exterior material side for an electricity storage device.

[0025] The resin layer A constituting the surface on the metal terminal side of the adhesive film for metal terminal 1 of the present disclosure has thermal adhesion to metal (the metal constituting the metal terminal). Therefore, when using the adhesive film for metal terminal 1 of the present disclosure, it is preferable to use the resin layer A by disposing it on the metal terminal side. For this reason, in the present disclosure, of the first resin layer 12a and the second resin layer 12b, at least the first resin layer 12a is formed by the resin layer A.

[0026] The surface of the adhesive film for metal terminal 1 of the present disclosure on the side of the exterior packaging material for an electricity storage device (for example, the second resin layer 12b) has thermal adhesion to a thermally adhesive resin layer described below. The resin layer A also has thermal adhesion to a thermally adhesive resin layer described below.

[0027] The resin layer A is a layer containing an acid-modified polyolefin. From the viewpoint of more suitably exerting the effects of the present disclosure, the resin layer A is preferably formed of an acid-modified polyolefin. That is, the resin layer A can be suitably constituted by an acid-modified polyolefin film.

[0028] The acid-modified polyolefin is not particularly limited as long as it is an acid-modified polyolefin, but preferred examples include polyolefins graft-modified with an unsaturated carboxylic acid or an anhydride thereof.

[0029] Specific examples of polyolefins to be modified with an acid include polyethylenes such as low-density polyethylene, medium-density polyethylene, high-density polyethylene, and linear low-density polyethylene; crystalline or amorphous polypropylenes such as homopolypropylene, block copolymers of polypropylene (e.g., block copolymers of propylene and ethylene), and random copolymers of polypropylene (e.g., random copolymers of propylene and ethylene); and ethylene-butene-propylene terpolymers. Among these polyolefins, polyethylene and polypropylene are preferred, and polypropylene is particularly preferred.

[0030] The polyolefin to be acid-modified may be a cyclic polyolefin. For example, a carboxylic acid-modified cyclic polyolefin is a polymer obtained by copolymerizing a part of the monomers constituting the cyclic polyolefin with an α,β-unsaturated carboxylic acid or an anhydride thereof, or by block-polymerizing or graft-polymerizing an α,β-unsaturated carboxylic acid or an anhydride thereof to the cyclic polyolefin.

[0031] The acid-modified cyclic polyolefin is a copolymer of an olefin and a cyclic monomer, and examples of the olefins that are the constituent monomers of the cyclic polyolefin include ethylene, propylene, 4-methyl-1-pentene, butadiene, and isoprene. Examples of the cyclic monomers that are the constituent monomers of the cyclic polyolefin include cyclic alkenes such as norbornene; specifically, cyclic dienes such as cyclopentadiene, dicyclopentadiene, cyclohexadiene, and norbornadiene. Among these polyolefins, preferred are cyclic alkenes, and more preferred are norbornene. Another example of the constituent monomer is styrene.

[0032] Examples of the carboxylic acid or anhydride thereof used for the acid modification include maleic acid, acrylic acid, itaconic acid, crotonic acid, maleic anhydride, itaconic anhydride, etc. When the resin layer A is analyzed by infrared spectroscopy, it is preferable that a peak derived from maleic anhydride is detected. For example, when maleic anhydride-modified polyolefin is measured by infrared spectroscopy, a peak derived from maleic anhydride is detected at a wave number of 1760 cm. -1 Nearby and wave number 1780cm -1 A peak derived from maleic anhydride is detected near the peak. When resin layer A is a layer composed of maleic anhydride-modified polyolefin, a peak derived from maleic anhydride is detected when measured by infrared spectroscopy. However, if the degree of acid modification is low, the peak becomes small and may not be detected. In that case, analysis can be performed by nuclear magnetic resonance spectroscopy.

[0033] Resin layer A has a crystallinity of 3 or more and 18 or less, as measured under the following conditions using an X-ray diffractometer. From the viewpoint of more suitably exerting the effects of the present disclosure, the crystallinity is preferably about 4 or more, more preferably about 5 to 6, and is preferably about 15 or less, more preferably about 10 or less. Preferred ranges include about 3 to 15, about 3 to 10, about 4 to 18, about 4 to 15, about 4 to 10, about 5 to 18, about 5 to 15, about 5 to 10, about 6 to 18, about 6 to 15, and about 6 to 10.

[0034] <Measurement of Crystallinity of Resin Layer A> The crystallinity is measured under the following conditions using an X-ray diffraction apparatus (for example, BL8S3 beamline, product name, Aichi Synchrotron Light Center). (Measurement conditions) The angle of X-ray irradiation is set to 0.09° with respect to the surface of resin layer A (0°). The measurement range is from the surface of resin layer A to a depth of 5 μm. For example, an R-AXIS is used as the X-ray detector, with a camera length of 500 mm, an X-ray wavelength of 0.92 Å, and an exposure time of 30 seconds.

[0035] (Analysis of resin layer A) Using the X-ray scattering data analysis software FI2D, data from the azimuth angle of 80deg to 100deg is extracted from the spectrum data of the 2D detector and integrated in the azimuth direction to obtain a 1D spectrum showing the intensity value against the diffraction angle 2θ. Furthermore, a straight line passing between the two points of 2θ=4.0deg and 2θ=16.0deg on the 1D spectrum is subtracted as the background. After that, the spectral intensity value A of the amorphous component is defined as the minimum value of the intensity value in the region A: 2θ=8.8deg to 9.8deg, and the crystal peak intensity values ​​P1, P2, P3, and P4 of the four crystal planes are defined as follows. P1: Peak top intensity value of the peak in the 2θ=7.0deg~9.2deg region P2: Peak top intensity value of the peak at 2θ=9.2deg~10.6deg P3: Peak top intensity value of the peak at 2θ=10.6deg~12.0deg P4: Peak top intensity value of the peak at 2θ=12.0deg~14.0deg The degree of crystallinity C is C=(P1+P2+P3+P4) / A The degree of orientation D is defined as D=P2 / P4.

[0036] Examples of methods for adjusting the crystallinity of the resin layer A containing an acid-modified polyolefin include the molding method (e.g., the type of molding method such as extrusion method or inflation method, cooling temperature, cooling time, line speed, clearance) when forming the resin layer A, the resin blend, and the selection of the resin type. For example, the crystallinity tends to be high when a slowly cooled or high-density resin is selected, and the crystallinity tends to be low when a rapidly cooled or low-density resin is selected, so the crystallinity of the resin layer A is adjusted to be within the above range.

[0037] In the adhesive film for metal terminal 1 of the present disclosure, the crystallinity of the resin layer A containing acid-modified polyolefin constituting at least one surface of the adhesive film for metal terminal 1 is set to a specific range of 3 to 18, thereby enabling excellent adhesion to the metal terminal to be exhibited. The reason for this can be considered as follows. That is, by setting the crystallinity of the resin layer A to the specific range, the crystallinity of the surface portion of the resin layer A that adheres to the metal terminal is appropriate, and the conformity to the shape of the metal terminal is appropriate (in other words, not too hard, not too soft), and as a result, it can be considered that excellent adhesion to the metal terminal is exhibited. Furthermore, by setting the crystallinity of the resin layer A to the specific range, it is also possible to suitably increase the seal strength when immersed in an electrolyte ("seal strength to metal terminal (after immersion in electrolyte)" described later). The reason for this can be considered as follows. That is, by setting the crystallinity of the resin layer A within the specific range, the crystallinity of the surface portion of the resin layer A that adheres to the metal terminal is appropriate, so that the resin layer A can appropriately conform to the shape of the metal terminal (in other words, it is neither too hard nor too soft), so that gaps are unlikely to occur between the resin layer A and the metal terminal, and the electrolyte is unlikely to penetrate into the interface between the resin layer A and the metal terminal. As a result, it can be considered that the seal strength when immersed in the electrolyte is suitably increased.

[0038] In addition, from the viewpoint of more suitably exerting the effects of the present disclosure, in the resin layer A, the uneven distribution degree of the island ratio of the sea-island structure is preferably about 1.00 or less, more preferably about 0.80 or less, even more preferably about 0.50 or less, and even more preferably about 0.35 or less, with the most preferred lower limit being 0, and preferred ranges being about 0 to 1.00, about 0 to 0.80, about 0 to 0.50, and about 0 to 0.35. In addition, by having the uneven distribution degree of the island ratio of the resin layer A be about 0.35 or less, the seal strength when the adhesive film for metal terminal 1 of the present disclosure is sealed to a metal terminal and then immersed in an electrolyte ("seal strength to metal terminal (after immersion in electrolyte)" described below) can be suitably increased. The uneven distribution degree of the island ratio is a value measured by the following measurement method. A small uneven distribution degree means that the variation of the sea-island in the plane of the resin layer A is small (the islands are evenly arranged in the plane). In general, since the electrolyte can easily permeate into the island parts, it can be considered that the even arrangement of the island parts suppresses the permeation of the electrolyte. For example, if the degree of uneven distribution is large, the islands are locally dense, and the electrolyte can easily permeate from the dense island parts.

[0039] <Measurement of uneven distribution of island ratio in resin layer A> [Pretreatment conditions] Cut the sample into strips and embed it in thermosetting resin (50℃, 24hr). Ru staining after trimming -Section preparation using an ultramicrotome (using a diamond knife: finishing thickness 80 nm) Os coating (1~3nm)

[0040] [SEM observation conditions] Measurement equipment: Commercially available SEM (e.g. Hitachi High-Technologies Corporation S-4800 TYPE II) Acceleration voltage: 5.0kV Emission current: 20μA WD: 5mm Detector: Upper+HA ·Measurement magnification: 10k times Resolution: 256dpi

[0041] [Image processing conditions] The electron microscope image is subjected to the following image processing to obtain a binary image. For image processing, we can use OpenCV, a Python image processing library. The image processing conditions are listed below. 1. Gaussian filter (kernel size 5px x 5px) 2. Enlarge the measurement image 8 times vertically and horizontally (completion method = CUBIC) 3. Remove noise using the fastNlMeansDenoising function (background color = black, fastNlMeansDenoising function parameters: h = 10, hForColorComponents = 10, templateWindowSize = 7, searchWindowSize = 21) 4. Binarize the image so that bright areas are white and dark areas are black (threshold = Otsu's threshold). 5.Morphological transformation-Open processing (kernel size = 45px x 15px) 6. Noise removal (removal of black areas less than 625px^2) 7. Noise removal (removal of white areas less than 75px^2) 8. Noise removal (removal of black areas less than 10000px^2) 9.Morphological transformation-Open processing (kernel size = 65px x 25px) 10.Morphological transformation-CLOSE processing (kernel size = 25px x 1px) A 504px x 504px area (corresponding to a 1μm x 1μm field of view) is cut out from the obtained binarized image, and the ratio of white areas in that area is defined as W (%). The ratio W of the white areas is calculated by cutting out 40 arbitrary points, The standard deviation of W at 40 locations divided by the average value of W at 40 locations is defined as the uneven distribution degree L of the sea-island structure.

[0042] Examples of methods for adjusting the uneven distribution of the island ratio in the resin layer A containing the acid-modified polyolefin include adjusting the molding method (e.g., the type of molding method such as extrusion method or inflation method, cooling temperature, cooling time, line speed) and resin blending when forming the resin layer A. For example, rapid cooling, fast line speed, and an increase in the amount of the resin island-forming component tend to make the island ratio unevenly distributed, while slow cooling, slow line speed, and a decrease in the amount of the resin island-forming component tend to make the island ratio less unevenly distributed. Therefore, adjustments are made to reduce the uneven distribution of the island ratio in the resin layer A.

[0043] In the adhesive film 1 for metal terminal of the present disclosure, the crystallinity of the resin layer A is within the range of 3 to 18, and the uneven distribution of the island ratio of the sea-island structure of the resin layer A containing acid-modified polyolefin, which constitutes at least one surface of the adhesive film 1 for metal terminal, is about 0.35 or less, so that the seal strength when immersed in an electrolyte ("seal strength for metal terminal (after immersion in electrolyte)" described later) can be further suitably increased. The reason for this can be considered as follows. That is, the sea part and the island part of the resin layer A are generally formed of different resins, and for example, when the resin layer A is formed of acid-modified polypropylene (having a resin sea-island structure in cross section), the sea part is generally formed of an acid-modified polypropylene component, and the island part is generally formed of a polyethylene component. The polyethylene part of the island part has a lower density than the acid-modified polypropylene part of the sea part, and is different from the sea part in terms of volume expansion coefficient, viscosity, swelling property in electrolyte, etc. Therefore, if the island portions are significantly distributed unevenly in the cross section of resin layer A, the properties will also be uneven when an electrolyte solution permeates into resin layer A, and the mechanical strength of resin layer A will be likely to decrease. In the present disclosure, by setting the degree of uneven distribution of the island portion ratio of the sea-island structure of resin layer A to about 0.35 or less, it is believed that the uneven distribution of the islands in the cross section of resin layer A is small, and the seal strength when immersed in an electrolyte solution can be increased.

[0044] In order to more suitably exert the effects of the present disclosure, the degree of orientation in the resin layer A is preferably about 0.5 or more, more preferably about 0.7 or more, and even more preferably about 1.0 or more, with a preferred upper limit of 5.5 or less, and preferred ranges include about 0.5 to 5.5, about 0.7 to 5.5, and 1.0 to 5.5. In addition, by having a degree of orientation of about 0.7 or more in the resin layer A, it is possible to suitably increase the seal strength ("seal strength to metal terminal (after immersion in electrolyte)" described below) when the adhesive film 1 for metal terminal of the present disclosure is sealed to a metal terminal and then immersed in an electrolyte. The degree of orientation is a value measured by the following measurement method.

[0045] <Measurement of the degree of orientation of resin layer A> The crystallinity is measured under the following conditions using an X-ray diffraction apparatus (for example, BL8S3 beamline, product name, Aichi Synchrotron Light Center). (Measurement conditions) The angle of X-ray irradiation is set to 0.09° with respect to the surface of resin layer A (0°). The measurement range is from the surface of resin layer A to a depth of 5 μm. For example, an R-AXIS is used as the X-ray detector, with a camera length of 500 mm, an X-ray wavelength of 0.92 Å, and an exposure time of 30 seconds.

[0046] (Analysis of resin layer A) Using the X-ray scattering data analysis software FI2D, data from the azimuth angle of 80deg to 100deg is extracted from the spectrum data of the 2D detector and integrated in the azimuth direction to obtain a 1D spectrum showing the intensity value against the diffraction angle 2θ. Furthermore, a straight line passing between the two points of 2θ=4.0deg and 2θ=16.0deg on the 1D spectrum is subtracted as the background. After that, the spectral intensity value A of the amorphous component is defined as the minimum value of the intensity value in the region A: 2θ=8.8deg to 9.8deg, and the crystal peak intensity values ​​P1, P2, P3, and P4 of the four crystal planes are defined as follows. P1: Peak top intensity value of the peak in the 2θ=7.0deg~9.2deg region P2: Peak top intensity value of the peak at 2θ=9.2deg~10.6deg P3: Peak top intensity value of the peak at 2θ=10.6deg~12.0deg P4: Peak top intensity value of the peak at 2θ=12.0deg~14.0deg The degree of crystallinity C is C=(P1+P2+P3+P4) / A The degree of orientation D is defined as D=P2 / P4.

[0047] The resin layer A may be formed of one type of resin component alone, or may be formed of a blended polymer in which two or more types of resin components are combined. From the viewpoint of film formability, the resin layer A is preferably formed of a blended polymer in which two or more types of resin components are combined. When using a blended polymer, the resin layer A preferably contains acid-modified polypropylene as the main component (a component of 50 mass% or more) and 50 mass% or less of another resin (preferably polyethylene from the viewpoint of improving flexibility). On the other hand, from the viewpoint of the electrolyte resistance of the resin layer A, it is preferable that the resin layer A contains acid-modified polypropylene alone as a resin.

[0048] The resin layer A may contain known additives as necessary.

[0049] For example, the resin layer A may contain a filler as necessary. When the resin layer A contains a filler, the filler functions as a spacer, making it possible to effectively suppress a short circuit between the metal terminal 2 and the barrier layer 33 of the exterior material 3 for an electrical storage device. The particle size of the filler is in the range of about 0.1 to 35 μm, preferably about 5.0 to 30 μm, and more preferably about 10 to 25 μm. The content of the filler is about 5 to 30 parts by mass, and more preferably about 10 to 20 parts by mass, relative to 100 parts by mass of the resin component forming the resin layer A.

[0050] As the filler, either inorganic or organic can be used. Examples of inorganic fillers include carbon (carbon, graphite), silica, aluminum oxide, barium titanate, iron oxide, silicon carbide, zirconium oxide, zirconium silicate, magnesium oxide, titanium oxide, calcium aluminate, calcium hydroxide, aluminum hydroxide, magnesium hydroxide, calcium carbonate, etc. Examples of organic fillers include fluororesin, phenolic resin, urea resin, epoxy resin, acrylic resin, benzoguanamine-formaldehyde condensate, melamine-formaldehyde condensate, polymethyl methacrylate crosslinked product, polyethylene crosslinked product, etc. From the viewpoints of shape stability, rigidity, and content resistance, aluminum oxide, silica, fluororesin, acrylic resin, and benzoguanamine-formaldehyde condensate are preferred, and among these, spherical aluminum oxide and silica are more preferred. As a method for mixing the filler into the resin component forming the resin layer A, a method in which the two are melt-blended in advance using a Banbury mixer or the like to prepare a master batch and then adjusted to a predetermined mixing ratio, or a method in which the filler is directly mixed with the resin component can be used.

[0051] The resin layer A may contain a pigment as necessary. As the pigment, various inorganic pigments can be used. As a specific example of the pigment, carbon (carbon, graphite) exemplified as the above filler can be preferably exemplified. Carbon (carbon, graphite) is a material generally used inside an electricity storage device, and there is no risk of dissolution in the electrolyte. In addition, the coloring effect is large, and a sufficient coloring effect can be obtained with an added amount that does not inhibit adhesion, and the apparent melt viscosity of the added resin can be increased without melting by heat. Furthermore, it is possible to prevent the pressurized part from becoming thin during heat adhesion (heat sealing), and to impart excellent sealing properties between the exterior material for electricity storage devices and the metal terminal.

[0052] When a pigment is added to the resin layer A, the amount of the pigment added is, for example, about 0.05 to 0.3 parts by mass, preferably about 0.1 to 0.2 parts by mass, per 100 parts by mass of the resin component forming the resin layer A when carbon black with a particle size of about 0.03 μm is used. By adding a pigment to the resin layer A, the presence or absence of the adhesive film 1 for metal terminals can be detected by a sensor or visually inspected. When a filler and a pigment are added to the resin layer A, the filler and the pigment may be added to the same resin layer A, but from the viewpoint of not impairing the thermal fusion property of the adhesive film 1 for metal terminals, it is preferable to add the filler and the pigment separately to different layers (for example, the first resin layer 12a, the second resin layer 12b, the intermediate layer 11, etc. described later).

[0053] From the viewpoint of more suitably achieving the effects of the present disclosure, the melting peak temperature of the resin layer A is preferably 125° C. or higher, more preferably about 130° C. or higher, and even more preferably about 135° C. or higher. From the same viewpoint, the melting peak temperature is, for example, 180° C. or lower, preferably 175° C. or lower, more preferably 170° C. or lower, even more preferably about 165° C. or lower, and even more preferably about 160° C. or lower. Preferred ranges of the melting peak temperature include about 125 to 180° C., about 125 to 175° C., about 125 to 170° C., about 125 to 165° C., about 125 to 160° C., about 130 to 180° C., about 130 to 175° C., about 130 to 170° C., about 130 to 165° C., about 130 to 160° C., about 135 to 180° C., about 135 to 175° C., about 135 to 170° C., about 135 to 165° C., and about 135 to 160° C. In the present disclosure, the method for measuring the melting peak temperature is as follows.

[0054] <Measurement of melting peak temperature> The melting peak temperature of each measurement sample is measured in accordance with the provisions of JIS K7121:2012 (Method of measuring transition temperature of plastics (JIS K7121:1987 Supplement 1)). The measurement is performed using a differential scanning calorimeter (DSC, for example, a differential scanning calorimeter Q200 manufactured by TA Instruments). The measurement sample is held at -50°C for 15 minutes, then heated from -50°C to 210°C at a heating rate of 10°C / min, the first melting peak temperature P (°C) is measured, and then held at 210°C for 10 minutes. Next, the temperature is lowered from 210°C to -50°C at a heating rate of 10°C / min and held for 15 minutes. Furthermore, the temperature is raised from -50°C to 210°C at a heating rate of 10°C / min, and the second melting peak temperature Q (°C) is measured. The flow rate of nitrogen gas is 50 ml / min. Using the above procedure, the melting peak temperature P (°C) measured the first time and the melting peak temperature Q (°C) measured the second time are determined. The melting peak temperature P (°C) measured the first time using the above procedure is adopted.

[0055] When the adhesive film 1 for metal terminal of the present disclosure is constituted by a single layer of resin layer A, the total thickness of the adhesive film 1 for metal terminal, which will be described later, corresponds to the thickness of resin layer A.

[0056] In addition, when the adhesive film 1 for metal terminal of the present disclosure is composed of multiple layers, from the viewpoint of more suitably achieving the effects of the present disclosure, the thickness of the resin layer A is preferably about 10 μm or more, more preferably about 15 μm or more, and even more preferably about 20 μm or more, and is also preferably about 120 μm or less, more preferably about 100 μm or less, and even more preferably 80 μm or less. Preferred ranges of the thickness of the resin layer A include about 10 to 120 μm, about 10 to 100 μm, about 10 to 80 μm, about 15 to 120 μm, about 15 to 100 μm, about 15 to 80 μm, about 20 to 120 μm, about 20 to 100 μm, and about 20 to 80 μm. From the viewpoint of improving the insulating properties of the adhesive film for metal terminal, the thickness of the resin layer A is preferably about 55 μm or more, more preferably about 60 μm or more, and is also preferably about 100 μm or less, more preferably about 90 μm or less, and preferred ranges include about 55 to 100 μm, about 55 to 90 μm, about 60 to 100 μm, and about 60 to 90 μm. When the adhesive film for metal terminal 1 of the present disclosure contains a plurality of resin layers A, it is preferable that the thickness of each of the resin layers A is the above-mentioned thickness.

[0057] As described above, the adhesive film 1 for metal terminal of the present disclosure can have a configuration in which at least a first resin layer 12a, an intermediate layer 11, and a second resin layer 12b are laminated in this order, for example, as shown in Fig. 6. In this configuration, since the first resin layer 12a is disposed on the metal terminal 2 side, at least the first resin layer 12a is defined as a resin layer A. Also, the second resin layer 12b is disposed on the electricity storage device exterior material 3 side. In this configuration, the first resin layer 12a and the second resin layer 12b are located on the surfaces of both sides, respectively.

[0058] The second resin layer 12b is a layer made of a resin. The second resin layer 12b may be formed of a resin layer A, or may be formed of a resin layer B different from the resin layer A (i.e., the resin layer B is a resin layer that does not contain an acid-modified polyolefin, or a resin layer that contains an acid-modified polyolefin but has a crystallinity outside the range of 3 to 18 as measured under the above-mentioned conditions using an X-ray diffraction device).

[0059] Moreover, the intermediate layer 11 may also be formed of the resin layer A, or may be formed of the resin layer B different from the resin layer A.

[0060] [Resin layer B] Examples of the resin constituting the resin layer B include polyolefin resins, polyamide resins, polyester resins, epoxy resins, acrylic resins, fluororesins, silicone resins, phenol resins, polyetherimides, polyimides, polycarbonates, and mixtures or copolymers thereof, and among these, polyolefin resins are particularly preferred. Examples of the polyolefin resins include polyolefins and acid-modified polyolefins.

[0061] As described below, the second resin layer 12b preferably contains a polyolefin resin (i.e., has a polyolefin skeleton), preferably contains a polyolefin, and is more preferably a layer formed of a polyolefin. The second resin layer 12b preferably contains a polyolefin or an acid-modified polyolefin among polyolefin resins, more preferably contains a polyolefin, and is more preferably a layer formed of a polyolefin.

[0062] Moreover, the intermediate layer 11 preferably contains a polyolefin resin (that is, has a polyolefin skeleton), preferably contains a polyolefin, and is more preferably a layer formed of a polyolefin.

[0063] The polyolefin resin is preferably a polypropylene resin in each of the second resin layer 12b and the resin layer B used in the intermediate layer 11. The polyolefin is preferably polypropylene, and the acid-modified polyolefin is preferably acid-modified polypropylene.

[0064] The resin layer B may be formed of one type of resin component alone, or may be formed of a blend polymer in which two or more resin components are combined. From the viewpoint of film formability, the resin layer B is preferably formed of a blend polymer in which two or more resin components are combined. In the case of a blend polymer, the resin layer B containing acid-modified polypropylene preferably contains acid-modified polypropylene as the main component (a component of 50% by mass or more) and 50% by mass or less of other resins (preferably polyethylene from the viewpoint of improving flexibility). In addition, the resin layer B containing polypropylene preferably contains polypropylene as the main component (a component of 50% by mass or more) and 50% by mass or less of other resins (preferably polyethylene from the viewpoint of improving flexibility). On the other hand, from the viewpoint of the electrolyte resistance of the resin layer B, the resin layer B containing acid-modified polypropylene preferably contains acid-modified polypropylene alone as a resin, and the resin layer B containing polypropylene preferably contains acid-modified polypropylene or polypropylene alone as a resin.

[0065] The polyester resin constituting the resin layer B is, for example, one that contains a polyester structure such as polyethylene terephthalate or polybutylene terephthalate. In addition to the polyethylene terephthalate structure or polybutylene terephthalate structure, the polyester structure may further contain a polyether structure, and the polyether structure may have a polycondensation structure of at least one of polytetramethylene ether glycol and neopentyl glycol and terephthalic acid of a polybutylene terephthalate structure. In addition to the polyethylene terephthalate structure or polybutylene terephthalate structure, the polyester structure may further contain another polyester structure, and the polyester structure may have a polycondensation structure of at least one selected from the group consisting of isophthalic acid, dodecanedioic acid, and sebacic acid and 1,4-butanediol of a polybutylene terephthalate structure.

[0066] The melting peak temperature of the resin layer B is preferably 125° C. or higher, more preferably about 130° C. or higher, and even more preferably about 135° C. or higher. The melting peak temperature is, for example, 180° C. or lower, preferably 175° C. or lower, more preferably 170° C. or lower, even more preferably about 165° C. or lower, and even more preferably about 160° C. or lower. Preferred ranges of the melting peak temperature include about 125 to 180°C, about 125 to 175°C, about 125 to 170°C, about 125 to 165°C, about 125 to 160°C, about 130 to 180°C, about 130 to 175°C, about 130 to 170°C, about 130 to 165°C, about 130 to 160°C, about 135 to 180°C, about 135 to 175°C, about 135 to 170°C, about 135 to 165°C, and about 135 to 160°C.

[0067] In addition, when the adhesive film for metal terminal 1 of the present disclosure has a resin layer B as the second resin layer 12b, from the viewpoint of more suitably achieving the effects of the present disclosure, the thickness of the resin layer B is preferably about 10 μm or more, more preferably about 15 μm or more, even more preferably about 20 μm or more, and is preferably about 120 μm or less, more preferably about 100 μm or less, even more preferably 80 μm or less. Preferred ranges of the thickness of the resin layer B include about 10 to 120 μm, about 10 to 100 μm, about 10 to 80 μm, about 15 to 120 μm, about 15 to 100 μm, about 15 to 80 μm, about 20 to 120 μm, about 20 to 100 μm, and about 20 to 80 μm.

[0068] In addition, when the adhesive film for metal terminal 1 of the present disclosure has a resin layer B as the intermediate layer 11, from the viewpoint of more suitably achieving the effects of the present disclosure, the thickness of the resin layer B is preferably about 10 μm or more, more preferably about 20 μm or more, even more preferably about 30 μm or more, and is preferably about 120 μm or less, more preferably about 110 μm or less, and even more preferably 100 μm or less. Preferred ranges of the thickness of the resin layer B include about 10 to 120 μm, about 10 to 110 μm, about 10 to 100 μm, about 20 to 120 μm, about 20 to 110 μm, about 20 to 100 μm, about 30 to 120 μm, about 30 to 110 μm, and about 30 to 100 μm.

[0069] The resin layer B may contain known additives (such as the above-mentioned fillers and pigments) in the same manner as the resin layer A. The types and amounts of the fillers and pigments to be added are the same as those of the resin layer A.

[0070] From the viewpoint of more suitably achieving the effects of the present disclosure, the total thickness of the adhesive film 1 for a metal terminal is, for example, about 50 μm or more, preferably about 80 μm or more, more preferably about 90 μm or more, even more preferably about 100 μm or more, and even more preferably about 180 μm or more. The total thickness of the adhesive film 1 for a metal terminal of the present disclosure is about 500 μm or less, preferably about 300 μm or less, more preferably about 250 μm or less, and even more preferably 200 μm or less. Preferred ranges for the total thickness of the adhesive film 1 for metal terminals of the present disclosure include about 50 to 500 μm, about 50 to 300 μm, about 50 to 250 μm, about 50 to 200 μm, about 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, about 180 to 500 μm, about 180 to 300 μm, about 180 to 250 μm, and about 180 to 200 μm. As a more specific example, when the adhesive film 1 for metal terminals of the present disclosure is used in a relatively small power storage device for a mobile phone, smartphone, or tablet, the total thickness is preferably about 60 to 100 μm, and when it is used in a relatively large power storage device for a power storage system or vehicle-mounted power storage device, the total thickness is preferably about 100 to 200 μm.

[0071] The adhesive film 1 for metal terminals of the present disclosure has a seal strength (initial) to a metal terminal, measured by the following method, of preferably about 20 N / 15 mm or more, more preferably about 25 N / 15 mm or more, and even more preferably about 30 N / 15 mm or more. The upper limit of the seal strength (initial) is usually about 80 N / 15 mm or less, and preferred ranges include about 20 to 80 N / 15 mm, about 25 to 80 N / 15 mm, and about 30 to 80 N / 15 mm.

[0072] <Measurement of seal strength (initial) for metal terminals> A piece of aluminum (JIS H4160:1994 A8079H-O) measuring 50 mm in length, 22.5 mm in width, and 0.4 mm in thickness is prepared as the metal terminal. The adhesive film for metal terminal is cut to a length of 45 mm and a width of 10 mm. The adhesive film for metal terminal is then placed on the metal terminal to obtain a metal terminal / adhesive film laminate. At this time, the metal terminal is laminated so that the vertical and horizontal directions of the metal terminal coincide with the length and width directions of the adhesive film for metal terminal, respectively, and the centers of the metal terminal and the adhesive film for metal terminal coincide with each other. The resin layer A of the adhesive film for metal terminal is placed on the metal terminal side. Next, a polytetrafluoroethylene film (PTFE film, thickness 100 μm) is placed on the adhesive film for metal terminal of the laminate (the surface of the adhesive film for metal terminal is covered with the PTFE film), and the laminate is placed on a press machine heated to 200 ° C (metal terminal is on the hot plate side), and a silicone sponge sheet is placed on top and left for 16 seconds at a pressure of 0.25 MPa to heat-seal the adhesive film to the metal terminal. The laminate after heat-sealing is naturally cooled to 25 ° C. Next, in an environment of 25 ° C, the adhesive film for metal terminal is peeled off from the metal terminal using a Tensilon universal material testing machine (for example, RTG-1210 manufactured by A & D Co., Ltd.). The maximum strength at the time of peeling is the adhesion strength to the metal terminal (N / 15 mm). The peeling speed is 50 mm / min, the peeling angle is 180 °, and the distance between the chucks is 30 mm, and the average value of three measurements is taken. The treatment of leaving the board stationary for 16 seconds in a heated and pressurized environment at a temperature of 200° C. and a surface pressure of 0.25 MPa is a treatment that simulates the heat and pressure applied in the temporary adhesion process and the main adhesion process.

[0073] Furthermore, the adhesive film 1 for metal terminals of the present disclosure has a seal strength to a metal terminal (after immersion in electrolyte) measured by the following method of preferably about 15 N / 15 mm or more, more preferably about 20 N / 15 mm or more, and even more preferably about 25 N / 15 mm or more. The upper limit of the seal strength (after immersion in electrolyte) is usually about 50 N / 15 mm or less, and preferred ranges include about 15 to 50 N / 15 mm, about 20 to 50 N / 15 mm, and about 25 to 50 N / 15 mm.

[0074] <Measurement of seal strength against metal terminals (after immersion in electrolyte)> A piece of aluminum (JIS H4160:1994 A8079H-O) measuring 50 mm in length, 22.5 mm in width, and 0.4 mm in thickness is prepared as the metal terminal. The adhesive film for metal terminal is cut to a length of 45 mm and a width of 10 mm. The adhesive film for metal terminal is then placed on the metal terminal to obtain a metal terminal / adhesive film laminate. At this time, the metal terminal is laminated so that the vertical and horizontal directions of the metal terminal coincide with the length and width directions of the adhesive film for metal terminal, respectively, and the centers of the metal terminal and the adhesive film for metal terminal coincide with each other. The resin layer A of the adhesive film for metal terminal is placed on the metal terminal side. Next, a polytetrafluoroethylene film (PTFE film, 100 μm thick) is placed on the adhesive film for metal terminals of the laminate (the surface of the adhesive film for metal terminals is covered with the PTFE film), and the laminate is placed on a press machine heated to 200°C (with the metal terminals facing the hot plate), and a silicone sponge sheet is placed on top. The laminate is left standing for 16 seconds at a pressure of 0.25 MPa to heat-seal the adhesive film to the metal terminals. The laminate after heat-sealing is allowed to cool naturally to 25°C. Next, the obtained laminate is placed in a 100 mL plastic bottle, and 100 g of electrolyte (EC (ethylene carbonate) / DMC (dimethyl carbonate) / DEC (diethyl carbonate) = 1:1:1) + 1000 ppm of pure water is mixed in and tightly sealed. The sealed container is placed in an oven at 85°C, and after 24 hours, it is taken out, the electrolyte is washed away with water, and the obtained laminate is left standing for 30 minutes to dry naturally. Next, in a 25°C environment, the adhesive film for metal terminals is peeled off from the metal terminal using a Tensilon universal material testing machine (e.g., A&D's RTG-1210). The maximum strength at the time of peeling is the adhesion strength to the metal terminal (N / 15mm). The peel speed is 50mm / min, the peel angle is 180°, and the chuck distance is 30mm, and the average value is taken as the average of three measurements. The process of leaving the film for 16 seconds in a heated and pressurized environment at a temperature of 200°C and a surface pressure of 0.25MPa is a process that simulates the heat and pressure applied in the temporary adhesion process and the main adhesion process described above.

[0075] The adhesive film for metal terminal of the present disclosure preferably has fine irregularities on at least one surface of the outermost layer. This can further improve the adhesion to the heat-sealable resin layer 35 of the exterior material for a storage device or the metal terminal. In addition, as a method for forming fine irregularities on the surface of the outermost layer of the adhesive film for metal terminal, a method of adding an additive such as fine particles to the outermost layer, a method of contacting a cooling roll having an irregular surface and shaping the surface, etc. are included. As the fine irregularities, the ten-point average roughness of the surface of the outermost layer is preferably about 0.1 μm or more, more preferably about 0.2 μm or more, and also preferably about 35 μm or less, more preferably about 10 μm or less, and preferred ranges include about 0.1 to 35 μm, about 0.1 to 10 μm, about 0.2 to 35 μm, and about 0.2 to 10 μm. The ten-point average roughness is a value measured using a small surface roughness measuring instrument, SURFTEST SJ-210, manufactured by Mitutoyo, in a method conforming to the provisions of JIS B0601:1994.

[0076] The adhesive film 1 for metal terminal of the present disclosure is preferably formed of a polyolefin resin. For example, the resin component contained in the adhesive film 1 for metal terminal of the present disclosure is preferably only an acid-modified polyolefin, or only an acid-modified polyolefin and a polyolefin. The preferred acid-modified polyolefin and polyolefin are as described in the resin layer A and the resin layer B.

[0077] The adhesive film 1 for metal terminal of the present disclosure is preferably composed of a laminate including, in this order, a first resin layer 12a, an intermediate layer 11, and a second resin layer 12b. Hereinafter, a preferred embodiment of the adhesive film 1 for metal terminal of the present disclosure will be described in detail, taking as an example a case in which the adhesive film 1 for metal terminal of the present disclosure is composed of a laminate including, in this order, at least a first resin layer 12a, an intermediate layer 11, and a second resin layer 12b, and the first resin layer 12a is a resin layer A.

[0078] When the adhesive film 1 for metal terminals of the present disclosure is disposed between the metal terminal 2 of the electricity storage device 10 and the exterior material 3 for the electricity storage device, the surface of the metal terminal 2 made of metal and the heat-sealable resin layer 35 (a layer formed of a heat-sealable resin such as polyolefin) of the exterior material 3 for the electricity storage device are bonded via the adhesive film 1 for metal terminals. The first resin layer 12a of the adhesive film 1 for metal terminals is disposed on the metal terminal 2 side, and the second resin layer 12b is disposed on the exterior material 3 for the electricity storage device, with the first resin layer 12a adhering to the metal terminal 2 and the second resin layer 12b adhering to the heat-sealable resin layer 35 of the exterior material 3 for the electricity storage device. The first resin layer 12a may be a single layer or multiple layers. The second resin layer 12b may be a single layer or multiple layers.

[0079] [First resin layer 12a and second resin layer 12b] As shown in Fig. 6, an adhesive film 1 for a metal terminal according to a preferred embodiment of the present disclosure has a first resin layer 12a on one side of an intermediate layer 11 and a second resin layer 12b on the other side. The first resin layer 12a is disposed on the metal terminal 2 side. The second resin layer 12b is disposed on the exterior material 3 for an electricity storage device side. In the adhesive film 1 for a metal terminal according to the present disclosure, the first resin layer 12a and the second resin layer 12b are located on the surfaces of both sides, respectively.

[0080] In the present disclosure, the first resin layer 12a is formed of the aforementioned resin layer A. The second resin layer 12b may be formed of the aforementioned resin layer A or may be formed of the aforementioned resin layer B.

[0081] The first resin layer 12a and the second resin layer 12b can each be formed, for example, by a resin film. When the first resin layer 12a and the second resin layer 12b are each formed by a resin film, when the first resin layer 12a and the second resin layer 12b are laminated with the intermediate layer 11 or the like to manufacture the adhesive film 1 for a metal terminal of the present disclosure, a preformed resin film may be used as the first resin layer 12a and the second resin layer 12b, respectively. In addition, the resins forming the first resin layer 12a and the second resin layer 12b may each be formed into a film on the surface of the intermediate layer 11 or the like by extrusion molding or coating, and used as the first resin layer 12a and the second resin layer 12b formed by the resin film.

[0082] The first resin layer 12a (resin layer A) disposed on the metal terminal 2 side preferably contains an acid-modified polyolefin as a main component, and more preferably contains an acid-modified polypropylene as a main component. Here, the main component means that the content of the resin component contained in the first resin layer 12a is, for example, 50% by mass or more, preferably 60% by mass or more, more preferably 70% by mass or more, even more preferably 80% by mass or more, even more preferably 90% by mass or more, even more preferably 95% by mass or more, even more preferably 98% by mass or more, and even more preferably 99% by mass or more. For example, the first resin layer 12a containing an acid-modified polypropylene as a main component means that the content of the acid-modified polypropylene among the resin components contained in the first resin layer 12a is, for example, 50% by mass or more, preferably 60% by mass or more, more preferably 70% by mass or more, even more preferably 80% by mass or more, even more preferably 90% by mass or more, even more preferably 95% by mass or more, even more preferably 98% by mass or more, and even more preferably 99% by mass or more.

[0083] As described above, the second resin layer 12b preferably contains a polyolefin resin (i.e., has a polyolefin skeleton), preferably contains a polyolefin, and is more preferably a layer formed of a polyolefin. The second resin layer 12b preferably contains, among polyolefin resins, a polyolefin or an acid-modified polyolefin, more preferably contains a polyolefin, and is more preferably a layer formed of a polyolefin. The polyolefin resin is preferably a polypropylene resin. The polyolefin is preferably polypropylene, and the acid-modified polyolefin is preferably polypropylene.

[0084] The second resin layer 12b arranged on the side of the exterior material 3 for an electric storage device more preferably contains polyolefin as a main component, and even more preferably contains polypropylene as a main component. Here, the main component means that the content of the resin component contained in the second resin layer 12b is, for example, 50% by mass or more, preferably 60% by mass or more, more preferably 70% by mass or more, even more preferably 80% by mass or more, even more preferably 90% by mass or more, even more preferably 95% by mass or more, even more preferably 98% by mass or more, and even more preferably 99% by mass or more. For example, the second resin layer 12b containing polypropylene as a main component means that the content of polypropylene of the resin component contained in the second resin layer 12b is, for example, 50% by mass or more, preferably 60% by mass or more, more preferably 70% by mass or more, even more preferably 80% by mass or more, even more preferably 90% by mass or more, even more preferably 95% by mass or more, even more preferably 98% by mass or more, and even more preferably 99% by mass or more.

[0085] The melting peak temperature of the second resin layer 12b is preferably 110° C. or higher, more preferably about 120° C. or higher, and even more preferably about 130° C. or higher. From the same viewpoint, the melting peak temperature is, for example, 200° C. or lower, preferably 190° C. or lower, more preferably 180° C. or lower, even more preferably about 170° C. or lower, and even more preferably about 160° C. or lower. Preferred ranges of the melting peak temperature include about 110 to 200°C, about 110 to 190°C, about 110 to 180°C, about 110 to 170°C, about 110 to 160°C, about 120 to 200°C, about 120 to 190°C, about 120 to 180°C, about 120 to 170°C, about 120 to 160°C, about 130 to 200°C, about 130 to 190°C, about 130 to 180°C, about 130 to 170°C, and about 130 to 160°C.

[0086] From the viewpoint of more suitably achieving the effects of the present disclosure, the thickness of the first resin layer 12a is preferably about 10 μm or more, more preferably about 15 μm or more, and even more preferably about 20 μm or more, and is preferably about 120 μm or less, more preferably about 100 μm or less, and even more preferably 80 μm or less. Preferred ranges of the thickness of the first resin layer 12a include about 10 to 120 μm, about 10 to 100 μm, about 10 to 80 μm, about 15 to 120 μm, about 15 to 100 μm, about 15 to 80 μm, about 20 to 120 μm, about 20 to 100 μm, and about 20 to 80 μm.

[0087] In order to more suitably achieve the effects of the present disclosure, the thickness of the second resin layer 12b is preferably about 10 μm or more, more preferably about 15 μm or more, and even more preferably about 20 μm or more, and is preferably about 120 μm or less, more preferably about 100 μm or less, and even more preferably 80 μm or less. Preferred ranges for the thickness of the second resin layer 12b include about 10 to 120 μm, about 10 to 100 μm, about 10 to 80 μm, about 15 to 120 μm, about 15 to 100 μm, about 15 to 80 μm, about 20 to 120 μm, about 20 to 100 μm, and about 20 to 80 μm.

[0088] [Middle layer 11] In the adhesive film for metal terminal 1, the intermediate layer 11 is a layer that functions as a support for the adhesive film for metal terminal 1.

[0089] The intermediate layer 11 may be formed of the resin layer A described above, or may be formed of the resin layer B described above.

[0090] The intermediate layer 11 can be formed, for example, from a resin film. When the intermediate layer 11 is formed from a resin film, a preformed resin film may be used as the intermediate layer 11 when the adhesive film for metal terminal 1 of the present disclosure is manufactured by laminating the intermediate layer 11 with the first resin layer 12a or the like. In addition, the resin forming the intermediate layer 11 may be formed into a film on the surface of the first resin layer 12a or the like by extrusion molding, coating, or the like, to form the intermediate layer 11 from a resin film.

[0091] The material forming the intermediate layer 11 is not particularly limited. Examples of the material forming the intermediate layer 11 include polyolefin resins, polyamide resins, polyester resins, epoxy resins, acrylic resins, fluororesins, silicone resins, phenol resins, polyetherimides, polyimides, polycarbonates, and mixtures and copolymers thereof, among which polyolefin resins are particularly preferred. That is, the material forming the intermediate layer 11 is preferably a resin containing a polyolefin skeleton, such as polyolefin or acid-modified polyolefin. The inclusion of a polyolefin skeleton in the resin constituting the intermediate layer 11 can be determined by, for example, infrared spectroscopy, gas chromatography mass spectrometry, or the like.

[0092] As described above, the intermediate layer 11 preferably contains a polyolefin resin, more preferably contains a polyolefin, and more preferably is a layer formed of a polyolefin. The layer formed of a polyolefin may be a stretched polyolefin film or an unstretched polyolefin film, but is preferably an unstretched polyolefin film. Specific examples of polyolefin include polyethylene such as low density polyethylene, medium density polyethylene, high density polyethylene, and linear low density polyethylene; crystalline or amorphous polypropylene such as homopolypropylene, block copolymer of polypropylene (e.g., block copolymer of propylene and ethylene), and random copolymer of polypropylene (e.g., random copolymer of propylene and ethylene); and ethylene-butene-propylene terpolymer. Among these polyolefins, polyethylene and polypropylene are preferred, and polypropylene is more preferred. In addition, since the intermediate layer 11 has excellent electrolyte resistance, it is preferred to contain homopolypropylene, more preferably be formed of homopolypropylene, and even more preferably be an unstretched homopolypropylene film.

[0093] Specific examples of polyamides include aliphatic polyamides such as nylon 6, nylon 66, nylon 610, nylon 12, nylon 46, and copolymers of nylon 6 and nylon 66; hexamethylenediamine-isophthalic acid-terephthalic acid copolymer polyamides such as nylon 6I, nylon 6T, nylon 6IT, and nylon 6I6T (I represents isophthalic acid, and T represents terephthalic acid) containing structural units derived from terephthalic acid and / or isophthalic acid, and aromatic polyamides such as polymetaxylylene adipamide (MXD6); alicyclic polyamides such as polyaminomethylcyclohexyl adipamide (PACM6); polyamides copolymerized with lactam components and isocyanate components such as 4,4'-diphenylmethane-diisocyanate, polyesteramide copolymers and polyetheresteramide copolymers which are copolymers of copolymerized polyamides with polyesters or polyalkylene ether glycols; and copolymers thereof. These polyamides may be used alone or in combination of two or more.

[0094] Specific examples of polyesters include polyethylene terephthalate, polybutylene terephthalate, polyethylene naphthalate, polybutylene naphthalate, polyethylene isophthalate, copolymerized polyesters mainly composed of ethylene terephthalate as repeating units, copolymerized polyesters mainly composed of butylene terephthalate as repeating units, etc. Specific examples of copolymerized polyesters mainly composed of ethylene terephthalate as repeating units include copolymer polyesters in which ethylene terephthalate as a main repeating unit is polymerized with ethylene isophthalate (hereinafter abbreviated as polyethylene (terephthalate / isophthalate)), polyethylene (terephthalate / isophthalate), polyethylene (terephthalate / adipate), polyethylene (terephthalate / sodium sulfoisophthalate), polyethylene (terephthalate / sodium isophthalate), polyethylene (terephthalate / phenyl-dicarboxylate), polyethylene (terephthalate / decane dicarboxylate), etc. Specific examples of copolymer polyesters containing butylene terephthalate as the main repeating unit include copolymer polyesters in which butylene terephthalate is the main repeating unit and is polymerized with butylene isophthalate (hereinafter abbreviated as polybutylene (terephthalate / isophthalate)), polybutylene (terephthalate / adipate), polybutylene (terephthalate / sebacate), polybutylene (terephthalate / decanedicarboxylate), polybutylene naphthalate, etc. These polyesters may be used alone or in combination of two or more.

[0095] The intermediate layer 11 may be formed of a nonwoven fabric made of the above-mentioned resin. When the intermediate layer 11 is a nonwoven fabric, it is preferable that the intermediate layer 11 is composed of the above-mentioned polyolefin resin, polyamide resin, or the like.

[0096] The melting peak temperature of the intermediate layer 11 is preferably 120° C. or higher, more preferably about 130° C. or higher, and even more preferably about 140° C. or higher. From the same viewpoint, the melting peak temperature is, for example, 210° C. or lower, preferably 200° C. or lower, more preferably 190° C. or lower, even more preferably about 180° C. or lower, and even more preferably about 170° C. or lower. Preferred ranges of the melting peak temperature include about 120 to 210°C, about 120 to 200°C, about 120 to 190°C, about 120 to 180°C, about 120 to 170°C, about 130 to 210°C, about 130 to 200°C, about 130 to 190°C, about 130 to 180°C, about 130 to 170°C, about 140 to 210°C, about 140 to 200°C, about 140 to 190°C, about 140 to 180°C, and about 140 to 170°C.

[0097] The crystallinity of the intermediate layer 11 measured under the following conditions using an X-ray diffraction device is preferably about 3.0 or more, more preferably about 3.5 or more, and even more preferably about 4.0 or more, and is preferably about 10.0 or less, more preferably about 9.0 or less, and even more preferably about 8.0 or less, with preferred ranges being about 3.0 to 10.0, about 3.0 to 9.0, about 3.0 to 8.0, about 3.5 to 10.0, about 3.5 to 9.0, about 3.5 to 8.0, about 4.0 to 10.0, about 4.0 to 9.0, and about 4.0 to 8.0. Conditions (apparatus, analysis, etc.) other than the following measurement conditions are the same as those for the measurement of the crystallinity of the resin layer A. (Measurement conditions: middle layer) The X-ray irradiation angles are 0.19° and 0.22° relative to the surface of the intermediate layer (0°). The X-ray detector used is R-AXIS, the camera length is 500 mm, the X-ray wavelength is 0.92 Å, and the exposure time is 30 seconds.

[0098] The intermediate layer 11 may be a single layer or multiple layers.

[0099] Moreover, by blending a colorant in the intermediate layer 11, the intermediate layer 11 can be a layer containing a colorant. Also, light transmittance can be adjusted by selecting a resin with low transparency. When the intermediate layer 11 is a film, a colored film or a film with low transparency can be used. When the intermediate layer 11 is a nonwoven fabric, a nonwoven fabric using a fiber or binder containing a colorant or a nonwoven fabric with low transparency can be used.

[0100] When the intermediate layer 11 is composed of a resin film, the surface of the intermediate layer 11 may be subjected to a known adhesion enhancing treatment such as corona discharge treatment, ozone treatment, or plasma treatment, if necessary.

[0101] From the viewpoint of more suitably achieving the effects of the present disclosure, the thickness of the intermediate layer 11 is preferably about 20 μm or more, more preferably about 30 μm or more, and even more preferably about 40 μm or more, and is preferably about 120 μm or less, more preferably about 110 μm or less, and even more preferably 100 μm or less. Preferred ranges for the thickness of the intermediate layer 11 include about 20 to 120 μm, about 20 to 110 μm, about 20 to 100 μm, about 30 to 120 μm, about 30 to 110 μm, about 30 to 100 μm, about 40 to 120 μm, about 40 to 110 μm, and about 40 to 100 μm.

[0102] From the same viewpoint, the ratio of the thickness of the intermediate layer 11 to the total thickness of the first resin layer 12a and the second resin layer 12b is preferably about 0.3 or more, more preferably about 0.4 or more, and also preferably about 1.0 or less, more preferably about 0.8 or less, with preferred ranges being about 0.3 to 1.0, about 0.3 to 0.8, about 0.4 to 1.0, and about 0.4 to 0.8. From the viewpoint of improving the insulating properties of the adhesive film 1 for metal terminals, the ratio is preferably about 0.55 or more, more preferably about 0.60 or more, and also preferably about 1.0 or less, more preferably about 0.9 or less, with preferred ranges being about 0.55 to 1.0, about 0.55 to 0.9, about 0.60 to 1.0, and about 0.60 to 0.9.

[0103] Furthermore, when the total thickness of the adhesive film 1 for metal terminal is taken as 100%, the proportion of the total thickness of the first resin layer 12a and the second resin layer 12b is preferably about 30 to 80%, and more preferably about 50 to 70%.

[0104] The adhesive film for metal terminal 1 of the present disclosure can be produced, for example, by laminating the first resin layer 12a and the second resin layer 12b, respectively, on both surfaces of the intermediate layer 11. The intermediate layer 11 can be laminated with the first resin layer 12a and the second resin layer 12b by a known method such as an extrusion lamination method, a T-die method, an inflation method, or a thermal lamination method.

[0105] The method for interposing the adhesive film 1 for a metal terminal between the metal terminal 2 and the exterior material 3 for an electricity storage device is not particularly limited, and for example, as shown in Figures 1 to 3, the adhesive film 1 for a metal terminal may be wrapped around the metal terminal 2 in a portion where the metal terminal 2 is sandwiched by the exterior material 3 for an electricity storage device. Furthermore, although not shown, in a portion where the metal terminal 2 is sandwiched by the exterior material 3 for an electricity storage device, the adhesive film 1 for a metal terminal may be disposed on both sides of the metal terminal 2 so as to cross the two metal terminals 2.

[0106] The adhesion promoter layer 13 is a layer provided as necessary for the purpose of firmly adhering the intermediate layer 11 to the first resin layer 12a and between the intermediate layer 11 and the second resin layer 12b (see FIG. 7). The adhesion promoter layer 13 may be provided on only one side between the intermediate layer 11 and the first resin layer 12a and between the intermediate layer 11 and the second resin layer 12b, or on both sides.

[0107] The adhesion promoter layer 13 can be formed using known adhesion promoters such as isocyanate-based, polyethyleneimine-based, polyester-based, polyurethane-based, polybutadiene-based, etc. From the viewpoint of obtaining strong adhesion strength, it is preferable to form the adhesion promoter using an isocyanate-based adhesion promoter among these. As the isocyanate-based adhesion promoter, one made of an isocyanate component selected from triisocyanate monomer and polymeric MDI has excellent laminate strength and is less likely to decrease in laminate strength at high temperatures. It is particularly preferable to form the adhesive using an adhesion promoter made of triphenylmethane-4,4',4"-triisocyanate, which is a triisocyanate monomer, or polymethylene polyphenyl polyisocyanate, which is a polymeric MDI (NCO content of approximately 30%, viscosity of 200 to 700 mPa s). It is also preferable to form the adhesive using a two-component curing adhesion promoter that uses tris(p-isocyanatephenyl)thiophosphate, which is a triisocyanate monomer, or a polyethyleneimine-based agent as the main agent and polycarbodiimide as the crosslinking agent.

[0108] The adhesion promoter layer 13 can be formed by coating and drying using a known coating method such as bar coating, roll coating, gravure coating, etc. The coating amount of the adhesion promoter is 20 to 100 mg / m in the case of an adhesion promoter made of triisocyanate. 2 Approximately, preferably 40 to 60 mg / m 2 In the case of adhesion promoters made of polymeric MDI, the concentration is 40 to 150 mg / m 2 Approximately, preferably 60 to 100 mg / m 2 In the case of a two-component curing adhesion promoter that uses polyethyleneimine as the base agent and polycarbodiimide as the crosslinking agent, the adhesive strength is about 5 to 50 mg / m 2 Approximately, preferably 10 to 30 mg / m 2 Triisocyanate monomer is a monomer with three isocyanate groups in one molecule, and polymeric MDI is a mixture of MDI and MDI oligomers formed by polymerization of MDI, and is represented by the following formula:

[0109] [ka]

[0110] In order to more suitably exert the effects of the present invention, it is preferable that the first resin layer 12a and the intermediate layer 11 are in contact with each other, and that the second resin layer 12b and the intermediate layer 11 are in contact with each other.

[0111] Specific examples of preferred laminate structures for the adhesive film 1 for metal terminals of the present disclosure include a three-layer structure in which a first resin layer formed from acid-modified polypropylene / a base material formed from polypropylene / a second resin layer formed from acid-modified polypropylene are laminated in this order; and a three-layer structure in which a first resin layer formed from acid-modified polypropylene / a base material formed from polypropylene / a second resin layer formed from polypropylene are laminated in this order. Of these, the latter three-layer structure is particularly preferred in terms of adhesion between the heat-sealable resin layer 35 and the second resin layer 12b of the exterior material 3 for an electricity storage device.

[0112] The adhesive film 1 for metal terminals of the present disclosure has a thermal shrinkage rate measured under the conditions described below of preferably 60% or less, more preferably 38% or less, even more preferably 30% or less, and even more preferably 20% or less, with preferred ranges being approximately 0 to 60%, approximately 0 to 38%, approximately 0 to 30%, and approximately 0 to 20%.

[0113] (Method of measuring heat shrinkage rate (%)) The adhesive film for metal terminals is cut into a size of 110 mm (MD) length x 10 mm (TD) width to prepare a test piece. Next, the length M (mm) of the test piece is measured using a metal ruler. Next, the end of the test piece in the length direction (approximately 10 mm) is fixed to the wire mesh with tape, and the test piece is hung from the wire mesh. In this state, it is placed in an oven heated to 190°C for 120 seconds, after which the test piece is removed together with the wire mesh and allowed to cool naturally in a room temperature (25°C) environment. Next, the length N (mm) of the test piece that has been naturally cooled to room temperature is measured using a metal ruler. The thermal shrinkage rate of the adhesive film for metal terminals is calculated using the formula below. Heat shrinkage rate (%) = (1-(length N / length M)) x 100

[0114] [Metal terminal 2] The adhesive film 1 for metal terminals of the present disclosure is used by being interposed between a metal terminal 2 and an exterior material 3 for an electricity storage device. The metal terminal 2 (tab) is a conductive member electrically connected to an electrode (positive electrode or negative electrode) of an electricity storage device element 4, and is made of a metal material. The metal material constituting the metal terminal 2 is not particularly limited, and examples thereof include aluminum, nickel, and copper. For example, the metal terminal 2 connected to the positive electrode of a lithium ion electricity storage device is usually made of aluminum or the like. Moreover, the metal terminal 2 connected to the negative electrode of a lithium ion electricity storage device is usually made of copper, nickel, or the like.

[0115] From the viewpoint of enhancing electrolyte resistance, it is preferable that the surface of the metal terminal 2 is subjected to a chemical conversion treatment. For example, when the metal terminal 2 is made of aluminum, specific examples of the chemical conversion treatment include known methods for forming a corrosion-resistant film such as a phosphate, a chromate, a fluoride, or a triazine thiol compound. Among the methods for forming a corrosion-resistant film, a phosphate chromate treatment using a material composed of three components: a phenolic resin, a chromium (III) fluoride compound, and phosphoric acid is preferable.

[0116] The size of the metal terminal 2 may be appropriately set depending on the size of the electricity storage device to be used. The thickness of the metal terminal 2 is preferably about 50 to 1000 μm, more preferably about 70 to 800 μm. The length of the metal terminal 2 is preferably about 1 to 200 mm, more preferably about 3 to 150 mm. The width of the metal terminal 2 is preferably about 1 to 200 mm, more preferably about 3 to 150 mm.

[0117] [Exterior materials for energy storage devices 3] The exterior material 3 for an electricity storage device may have a laminated structure including at least a base material layer 31, a barrier layer 33, and a heat-sealable resin layer 35 in this order. FIG. 8 shows an example of a cross-sectional structure of the exterior material 3 for an electricity storage device, in which the base material layer 31, an adhesive layer 32 provided as needed, a barrier layer 33, an adhesive layer 34 provided as needed, and a heat-sealable resin layer 35 are laminated in this order. In the exterior material 3 for an electricity storage device, the base material layer 31 is the outer layer, and the heat-sealable resin layer 35 is the innermost layer. When assembling the electricity storage device, the heat-sealable resin layers 35 located on the periphery of the electricity storage device element 4 are brought into contact with each other and heat-sealed to seal the electricity storage device element 4, thereby sealing the electricity storage device element 4. Note that FIGS. 1 to 3 show an electricity storage device 10 using an embossed type exterior material 3 for an electricity storage device formed by embossing or the like, but the exterior material 3 for an electricity storage device may be an unformed pouch type. The pouch type includes three-sided seal, four-sided seal, pillow type, etc., and any type may be used.

[0118] The thickness of the laminate constituting the electricity storage device exterior material 3 is not particularly limited, but the upper limit, from the viewpoints of cost reduction, energy density improvement, and the like, is, for example, about 190 μm or less, preferably about 180 μm or less, about 160 μm or less, about 155 μm or less, about 140 μm or less, about 130 μm or less, and about 120 μm or less. The lower limit, from the viewpoint of maintaining the function of the electricity storage device exterior material 3 to protect the electricity storage device element 4, is preferably about 35 μm or more, about 45 μm or more, about 60 μm or more, and about 80 μm or more. Preferred ranges are, for example, about 35 to 190 μm, about 35 to 180 μm, and about 35 to 160 μm. degree, about 35-155μm, about 35-140μm, about 35-130μm, about 35-120μm, about 45-190μm, about 45-180μm, 45 ~160μm, 45~155μm, 45~140μm, 45~130μm, 45~120μm, 60~190μm, 60~180μm Examples of the thickness include about 60 to 160 μm, about 60 to 155 μm, about 60 to 140 μm, about 60 to 130 μm, about 60 to 120 μm, about 80 to 190 μm, about 80 to 180 μm, about 80 to 160 μm, about 80 to 155 μm, about 80 to 140 μm, about 80 to 130 μm, and about 80 to 120 μm.

[0119] (Base material layer 31) In the packaging material 3 for an electricity storage device, the base material layer 31 is a layer that functions as the base material of the packaging material for an electricity storage device, and is a layer that forms the outermost layer side.

[0120] The material for forming the base layer 31 is not particularly limited, as long as it has insulating properties. Examples of materials for forming the base layer 31 include polyester, polyamide, epoxy, acrylic resin, fluororesin, polyurethane, silicone resin, phenol, polyetherimide, polyimide, and mixtures and copolymers thereof. Polyesters such as polyethylene terephthalate and polybutylene terephthalate have the advantage of being excellent in electrolyte resistance and being unlikely to cause whitening due to adhesion of electrolyte, and are preferably used as materials for forming the base layer 31. In addition, polyamide films have excellent stretchability and can prevent whitening due to resin cracking of the base layer 31 during molding, and are preferably used as materials for forming the base layer 31.

[0121] The base layer 31 may be formed of a uniaxially or biaxially stretched resin film, or may be formed of an unstretched resin film. Among them, a uniaxially or biaxially stretched resin film, especially a biaxially stretched resin film, is preferably used as the base layer 31 because its heat resistance is improved by oriented crystallization.

[0122] Among these, the resin film forming the base layer 31 is preferably nylon or polyester, and more preferably biaxially oriented nylon or biaxially oriented polyester.

[0123] The base layer 31 may be laminated with resin films of different materials in order to improve pinhole resistance and insulation when used as a package for a power storage device. Specifically, it may be a multi-layer structure in which a polyester film and a nylon film are laminated, or a multi-layer structure in which a biaxially oriented polyester and a biaxially oriented nylon are laminated. When the base layer 31 has a multi-layer structure, each resin film may be bonded via an adhesive, or may be directly laminated without an adhesive. When bonding without an adhesive, for example, a method of bonding in a hot melt state such as a co-extrusion method, a sand lamination method, or a thermal lamination method may be used.

[0124] The base layer 31 may be made to have low friction in order to improve formability. When making the base layer 31 low-friction, the coefficient of friction of the surface is not particularly limited, but may be, for example, 1.0 or less. To make the base layer 31 low-friction, for example, matte treatment, formation of a thin film layer of a slip agent, a combination of these, etc. may be used.

[0125] The thickness of the base layer 31 is, for example, about 10 to 50 μm, and preferably about 15 to 30 μm.

[0126] (Adhesive layer 32) In the exterior material 3 for an electricity storage device, the adhesive layer 32 is a layer that is disposed on the base material layer 31 as necessary in order to impart adhesion to the base material layer 31. That is, the adhesive layer 32 is provided between the base material layer 31 and the barrier layer 33.

[0127] The adhesive layer 32 is formed of an adhesive capable of bonding the base material layer 31 and the barrier layer 33. The adhesive used to form the adhesive layer 32 may be a two-component curing adhesive or a one-component curing adhesive. The adhesion mechanism of the adhesive used to form the adhesive layer 32 is not particularly limited, and may be any of a chemical reaction type, a solvent volatilization type, a thermal melting type, a thermal pressure type, and the like.

[0128] The resin component of the adhesive that can be used to form the adhesive layer 32 is preferably a polyurethane-based two-component curing adhesive; or a blend resin of polyamide, polyester, or these with modified polyolefin, from the viewpoint of having excellent ductility, durability under high humidity conditions, yellowing prevention, and thermal degradation prevention during heat sealing, and of effectively suppressing a decrease in the laminate strength between the base layer 31 and the barrier layer 33 and preventing the occurrence of delamination.

[0129] The adhesive layer 32 may be multi-layered with different adhesive components. When the adhesive layer 32 is multi-layered with different adhesive components, it is preferable to select a resin having excellent adhesion to the base material layer 31 as the adhesive component arranged on the base material layer 31 side, and an adhesive component having excellent adhesion to the barrier layer 33 as the adhesive component arranged on the barrier layer 33 side, from the viewpoint of improving the laminate strength between the base material layer 31 and the barrier layer 33. When the adhesive layer 32 is multi-layered with different adhesive components, specifically, the adhesive component arranged on the barrier layer 33 side is preferably an acid-modified polyolefin, a metal-modified polyolefin, a mixed resin of polyester and acid-modified polyolefin, a resin containing a copolymerized polyester, or the like.

[0130] The thickness of the adhesive layer 32 is, for example, about 2 to 50 μm, and preferably about 3 to 25 μm.

[0131] (Barrier layer 33) In the electrical storage device exterior material 3, the barrier layer 33 is a layer that has the function of preventing water vapor, oxygen, light, and the like from penetrating into the electrical storage device in addition to improving the strength of the electrical storage device exterior material. The barrier layer 33 is preferably a metal layer, that is, a layer formed of a metal. Specific examples of metals constituting the barrier layer 33 include aluminum, stainless steel, and titanium, and preferably aluminum. The barrier layer 33 can be formed, for example, of a metal foil, a metal vapor deposition film, an inorganic oxide vapor deposition film, a carbon-containing inorganic oxide vapor deposition film, or a film provided with these vapor deposition films, and is preferably formed of a metal foil, and more preferably formed of an aluminum foil. From the viewpoint of preventing the occurrence of wrinkles or pinholes in the barrier layer 33 during the manufacture of the exterior material for an electricity storage device, it is more preferable that the barrier layer be formed from a soft aluminum foil such as annealed aluminum (JIS H4160:1994 A8021H-O, JIS H4160:1994 A8079H-O, JIS H4000:2014 A8021P-O, JIS H4000:2014 A8079P-O).

[0132] The thickness of the barrier layer 33 is preferably about 10 to 200 μm, more preferably about 20 to 100 μm, about 20 to 45 μm, about 45 to 65 μm, or about 65 to 85 μm, from the viewpoint of making the exterior material for an electricity storage device thin while making it difficult for pinholes to occur during molding.

[0133] Moreover, it is preferable that at least one surface, and preferably both surfaces, of the barrier layer 33 are subjected to a chemical conversion treatment in order to stabilize adhesion, prevent dissolution or corrosion, etc. Here, the chemical conversion treatment refers to a treatment for forming a corrosion-resistant film on the surface of the barrier layer.

[0134] (adhesive layer 34) In the packaging material 3 for an electricity storage device, the adhesive layer 34 is a layer that is provided, if necessary, between the barrier layer 33 and the heat-sealable resin layer 35 in order to firmly bond the heat-sealable resin layer 35.

[0135] The adhesive layer 34 is formed of an adhesive capable of bonding the barrier layer 33 and the heat-fusible resin layer 35. The composition of the adhesive used to form the adhesive layer is not particularly limited, and examples thereof include a resin composition containing an acid-modified polyolefin. Examples of the acid-modified polyolefin include the same ones as those exemplified for the first resin layer 12a and the second resin layer 12b.

[0136] The thickness of the adhesive layer 34 is, for example, about 1 to 40 μm, and preferably about 2 to 30 μm.

[0137] (Thermal adhesive resin layer 35) In the electricity storage device packaging material 3, the heat-sealable resin layer 35 corresponds to the innermost layer, and is a layer that seals the electricity storage device elements by being heat-sealed to each other when the electricity storage device is assembled.

[0138] The resin component used in the heat-fusible resin layer 35 is not particularly limited as long as it is heat-fusible, and examples thereof include polyolefin and cyclic polyolefin.

[0139] Specific examples of the polyolefin include polyethylenes such as low-density polyethylene, medium-density polyethylene, high-density polyethylene, and linear low-density polyethylene; crystalline or amorphous polypropylenes such as homopolypropylene, block copolymers of polypropylene (e.g., block copolymers of propylene and ethylene), and random copolymers of polypropylene (e.g., random copolymers of propylene and ethylene); and ethylene-butene-propylene terpolymers. Among these polyolefins, polyethylene and polypropylene are preferable.

[0140] The cyclic polyolefin is a copolymer of an olefin and a cyclic monomer, and examples of the olefins constituting the cyclic polyolefin include ethylene, propylene, 4-methyl-1-pentene, butadiene, and isoprene. Examples of the cyclic monomers constituting the cyclic polyolefin include cyclic alkenes such as norbornene; specifically, cyclic dienes such as cyclopentadiene, dicyclopentadiene, cyclohexadiene, and norbornadiene. Among these polyolefins, preferred are cyclic alkenes, and more preferred are norbornene. Another example of the constituting monomer is styrene.

[0141] Among these resin components, preferred are crystalline or amorphous polyolefins, cyclic polyolefins, and blend polymers thereof; more preferred are polyethylene, polypropylene, copolymers of ethylene and norbornene, and blend polymers of two or more of these.

[0142] The heat-sealable resin layer 35 may be formed of one type of resin component alone, or may be formed of a blend polymer of two or more types of resin components. The heat-sealable resin layer 35 may be formed of only one layer, or may be formed of two or more layers of the same or different resin components. It is particularly preferable that the second resin layer 12b and the heat-sealable resin layer 35 use the same resin, since this improves the adhesion between these layers.

[0143] The thickness of the heat-sealable resin layer 35 is not particularly limited, but may be about 2 to 2000 μm, preferably about 5 to 1000 μm, and more preferably about 10 to 500 μm. The thickness of the heat-sealable resin layer 35 may be, for example, about 100 μm or less, preferably about 85 μm or less, and more preferably about 15 to 85 μm. For example, when the thickness of the adhesive layer 5 described later is 10 μm or more, the thickness of the heat-sealable resin layer 35 is preferably about 85 μm or less, and more preferably about 15 to 45 μm. For example, when the thickness of the adhesive layer 5 described later is less than 10 μm or when the adhesive layer 5 is not provided, the thickness of the heat-sealable resin layer 35 is preferably about 20 μm or more, and more preferably about 35 to 85 μm.

[0144] The exterior material for an electricity storage device of the present disclosure can also be in the form of a kit including the exterior material for an electricity storage device for use in an electricity storage device and the adhesive film for a metal terminal of the present disclosure. In this case, the electricity storage device to which the kit is applied includes at least an electricity storage device element having a positive electrode, a negative electrode, and an electrolyte, an exterior material for an electricity storage device that seals the electricity storage device element, and metal terminals that are electrically connected to the positive electrode and the negative electrode and protrude outside the exterior material for an electricity storage device. The kit of the present disclosure is used such that the adhesive film for a metal terminal of the present disclosure is interposed between the metal terminal and the exterior material for an electricity storage device when used.

[0145] 2. Energy storage devices The electricity storage device 10 of the present disclosure comprises at least an electricity storage device element 4 having a positive electrode, a negative electrode, and an electrolyte, an exterior material for an electricity storage device 3 that seals the electricity storage device element 4, and a metal terminal 2 that is electrically connected to each of the positive electrode and the negative electrode and protrudes to the outside of the exterior material for an electricity storage device 3. The electricity storage device 10 of the present disclosure is characterized in that an adhesive film for a metal terminal 1 of the present disclosure is interposed between the metal terminal 2 and the exterior material for an electricity storage device 3. That is, the electricity storage device 10 of the present disclosure can be manufactured by a method including a step of interposing an adhesive film for a metal terminal 1 of the present disclosure between the metal terminal 2 and the exterior material for an electricity storage device 3.

[0146] Specifically, an electric storage device element 4 having at least a positive electrode, a negative electrode, and an electrolyte is covered with an electric storage device exterior material 3 in a state in which metal terminals 2 connected to the positive and negative electrodes are protruding outward, and an adhesive film 1 for metal terminals of the present disclosure is interposed between the metal terminals 2 and a heat-sealable resin layer 35, and the electric storage device element 4 is covered so that a flange portion (a region where the heat-sealable resin layers 35 contact each other, the peripheral portion 3a of the electric storage device exterior material 3) of the electric storage device exterior material 3 can be formed, and the heat-sealable resin layers 35 of the flange portion are heat-sealed to each other to provide an electric storage device 10 using the electric storage device exterior material 3. When the electric storage device element 4 is housed using the electric storage device exterior material 3, the heat-sealable resin layer 35 of the electric storage device exterior material 3 is used so that it faces inside (the surface in contact with the electric storage device element 4).

[0147] The exterior material for an electric storage device of the present disclosure can be suitably used for an electric storage device such as a battery (including a condenser, a capacitor, etc.). The exterior material for an electric storage device of the present disclosure may be used for either a primary battery or a secondary battery, but is preferably a secondary battery. The type of secondary battery to which the exterior material for an electric storage device of the present disclosure is applied is not particularly limited, and examples thereof include lithium ion batteries, lithium ion polymer batteries, all-solid batteries, semi-solid batteries, quasi-solid batteries, polymer batteries, all-resin batteries, lead-acid batteries, nickel-hydrogen batteries, nickel-cadmium batteries, nickel-iron batteries, nickel-zinc batteries, silver oxide-zinc batteries, metal-air batteries, polyvalent cation batteries, condensers, capacitors, etc. Among these secondary batteries, examples of suitable applications of the exterior material for an electric storage device of the present disclosure include lithium ion batteries and lithium ion polymer batteries. EXAMPLES

[0148] The present disclosure will be described in detail below with reference to examples and comparative examples. However, the present disclosure is not limited to the examples.

[0149] <Production of adhesive film for metal terminals> Example 1 Using an extruder and a T-die casting device, polypropylene (PP layer, homopolypropylene, melting peak temperature 163 ° C, thickness 50 μm) as an intermediate layer was extruded on one side as a second resin layer on the exterior material side (PP layer, melting peak temperature 140 ° C), and carbon black-containing maleic anhydride-modified polypropylene (PPa layer, melting peak temperature 140 ° C) was extruded on the other side as a first resin layer (resin layer A) on the metal terminal side, each with a thickness of 50 μm, to obtain an adhesive film (total thickness 150 μm) in which the first resin layer (resin layer A, PPa layer, melting peak temperature 140 ° C, thickness 50 μm) / substrate (PP layer, melting peak temperature 163 ° C, thickness 50 μm) / second resin layer (PP layer, melting peak temperature 140 ° C, thickness 50 μm) were laminated in order. The first resin layer, which was the resin layer A, was manufactured under the film formation temperature standard condition, film formation speed standard condition, and cooling standard condition to adjust the crystallinity.

[0150] Example 2 Using an extruder and a T-die casting device, a maleic anhydride-modified polypropylene (PPa layer, melting peak temperature 140°C) was extruded as the second resin layer on the exterior material side on one side of a polypropylene intermediate layer (PP layer, random polypropylene, melting peak temperature 143°C, thickness 100μm), and a maleic anhydride-modified polypropylene (PPa layer, melting peak temperature 140°C) was extruded as the first resin layer (resin layer A) on the metal terminal side on the other side, each with a thickness of 25μm, to obtain an adhesive film (total thickness 150μm) in which the first resin layer (resin layer A, PPa layer, melting peak temperature 140°C, thickness 25μm) / base material (PP layer, melting peak temperature 143°C, thickness 100μm) / second resin layer (PPa layer, melting peak temperature 140°C, thickness 25μm) were laminated in this order. The first resin layer, which was used as resin layer A, was produced under conditions that were significantly lower than the film-forming temperature standard, significantly slower than the film-forming speed standard, and more rapid than the cooling standard, thereby adjusting the crystallinity.

[0151] Example 3 Using an extruder and a T-die casting device, polypropylene (PP layer, melting peak temperature 140°C) was extruded to a thickness of 40μm as the second resin layer on the exterior material side onto one side of the carbon black-containing polypropylene (PP layer, homopolypropylene, melting peak temperature 160°C, thickness 60μm) as the intermediate layer, and maleic anhydride-modified polypropylene (PPa layer, melting peak temperature 140°C) was extruded to a thickness of 50μm as the first resin layer (resin layer A) on the metal terminal side onto the other side, to obtain an adhesive film (total thickness 150μm) in which the first resin layer (resin layer A, PPa layer, melting peak temperature 140°C, thickness 50μm) / base material (PP layer, melting peak temperature 160°C, thickness 60μm) / second resin layer (PP layer, melting peak temperature 140°C, thickness 40μm) were laminated in this order. The first resin layer, which was used as resin layer A, was produced under conditions of a lower film-forming temperature standard, a faster film-forming speed standard, and a slower cooling standard, thereby adjusting the crystallinity.

[0152] Example 4 Using an inflation extrusion device, a maleic anhydride-modified polypropylene (PPa layer, melting peak temperature 140°C) was extruded as the second resin layer on the exterior material side on one side of a polypropylene intermediate layer (PP layer, homopolypropylene, melting peak temperature 160°C, thickness 80μm), and a maleic anhydride-modified polypropylene (PPa layer, melting peak temperature 140°C) was extruded as the first resin layer (resin layer A) on the metal terminal side on the other side, each with a thickness of 35μm, to obtain an adhesive film (total thickness 150μm) in which the first resin layer (resin layer A, PPa layer, melting peak temperature 140°C, thickness 35μm) / substrate (PP layer, melting peak temperature 160°C, thickness 80μm) / second resin layer (PPa layer, melting peak temperature 140°C, thickness 35μm) were laminated in this order. The first resin layer, which was used as resin layer A, was produced under conditions of a lower film-forming temperature standard, a significantly slower film-forming speed standard, and a significantly slower cooling standard, thereby adjusting the crystallinity.

[0153] Example 5 Using an extruder and a T-die casting device, polypropylene (PP layer, homopolypropylene, melting peak temperature 163 ° C, thickness 80 μm) as an intermediate layer was extruded on one side as a second resin layer on the exterior material side (PP layer, melting peak temperature 140 ° C), and carbon black-containing maleic anhydride-modified polypropylene (PPa layer, melting peak temperature 140 ° C) was extruded on the other side as a first resin layer (resin layer A) on the metal terminal side with a thickness of 60 μm, respectively, to obtain an adhesive film (total thickness 200 μm) in which the first resin layer (resin layer A, PPa layer, melting peak temperature 140 ° C, thickness 60 μm) / substrate (PP layer, melting peak temperature 163 ° C, thickness 80 μm) / second resin layer (PP layer, melting peak temperature 140 ° C, thickness 60 μm) were laminated in order. The first resin layer, which was the resin layer A, was manufactured under the film formation temperature standard condition, film formation speed standard condition, and cooling standard condition to adjust the crystallinity.

[0154] Example 6 Using an extruder and a T-die casting device, polypropylene (PP layer, homopolypropylene, melting peak temperature 163 ° C, thickness 80 μm) as an intermediate layer was extruded on one side as a second resin layer on the exterior material side (PP layer, melting peak temperature 140 ° C), and carbon black-containing maleic anhydride-modified polypropylene (PPa layer, melting peak temperature 140 ° C) was extruded on the other side as a first resin layer (resin layer A) on the metal terminal side with a thickness of 60 μm, respectively, to obtain an adhesive film (total thickness 200 μm) in which the first resin layer (resin layer A, PPa layer, melting peak temperature 140 ° C, thickness 60 μm) / substrate (PP layer, melting peak temperature 163 ° C, thickness 80 μm) / second resin layer (PP layer, melting peak temperature 140 ° C, thickness 60 μm) were laminated in order. The first resin layer, which was the resin layer A, was manufactured under the film formation temperature standard condition, film formation speed standard condition, and cooling standard condition to adjust the crystallinity.

[0155] Example 7 Using an extruder and a T-die casting device, polypropylene (PP layer, melting peak temperature 140°C) was extruded to a thickness of 60 μm as the second resin layer on the exterior material side onto one side of the polypropylene (PP layer, homopolypropylene, melting peak temperature 163°C, thickness 80 μm) as the intermediate layer, and carbon black-containing maleic anhydride-modified polypropylene (PPa layer, melting peak temperature 140°C) was extruded to a thickness of 20 μm onto the other side, and the first resin layer ( As the resin layer A), maleic anhydride modified polypropylene (PPa layer, melting peak temperature 140 ° C.) was extruded to a thickness of 40 μm, and the first resin layer (resin layer A, PPa layer, melting peak temperature 140 ° C., thickness 40 μm) / third resin layer (PPa layer, melting peak temperature 140 ° C., thickness 20 μm) / substrate (PP layer, melting peak temperature 163 ° C., thickness 80 μm) / second resin layer (PP layer, melting peak temperature 140 ° C., thickness 60 μm) were laminated in order to obtain an adhesive film (total thickness 200 μm). The first resin layer as the resin layer A was manufactured under the film formation temperature standard condition, film formation speed standard condition, and cooling standard condition to adjust the crystallinity.

[0156] Comparative Example 1 An acid-modified polypropylene film (melting peak temperature 140°C, thickness 100μm) was prepared as an adhesive film for metal terminals by using an extruder and T-die casting.

[0157] <Measurement of Crystallinity of Resin Layer A and Intermediate Layer> The crystallinity of the first resin layer (resin layer A) and the intermediate layer of the adhesive film of Example 1-7 was measured under the following conditions using an X-ray diffraction device (product name BL8S3 beamline of Aichi Synchrotron Light Center). In addition, the crystallinity of the acid-modified polypropylene film of the adhesive film of Comparative Example 1 was measured in the same manner as in Example 1-7. The results are shown in Table 1. (Measurement conditions: resin layer A) The angle of X-ray irradiation is 0.09° relative to the surface of resin layer A (0°). The measurement range is from the surface of resin layer A to a depth of 5 μm. The camera length of the X-ray detector is 500 mm, the X-ray wavelength is 0.92 Å, and the exposure time is 30 seconds. (Measurement conditions: middle layer) The X-ray irradiation angles are 0.19° and 0.22° relative to the surface of the intermediate layer (0°). The X-ray detector used is R-AXIS, the camera length is 500 mm, the X-ray wavelength is 0.92 Å, and the exposure time is 30 seconds.

[0158] (Analysis of the middle layer) Using the X-ray scattering data analysis software FI2D, data from the azimuth angle of 80deg to 100deg is extracted from the spectrum data of the 2D detector and integrated in the azimuth direction to obtain a 1D spectrum showing the intensity value against the diffraction angle 2θ. Furthermore, a straight line passing between the two points of 2θ=4.0deg and 2θ=16.0deg on the 1D spectrum is subtracted as the background. After that, the spectral intensity value A of the amorphous component is defined as the minimum value of the intensity value in the region A: 2θ=8.8deg to 9.8deg, and the crystal peak intensity values ​​P1, P2, P3, and P4 of the four crystal planes are defined as follows. P1: Peak top intensity value of the peak in the 2θ=7.0deg~9.2deg region P2: Peak top intensity value of the peak at 2θ=9.2deg~10.6deg P3: Peak top intensity value of the peak at 2θ=10.6deg~12.0deg P4: Peak top intensity value of the peak at 2θ=12.0deg~14.0deg The value obtained by subtracting the value of P1+P2+P3+P4 when measured at an X-ray irradiation angle of 0.19° from the value of P1+P2+P3+P4 when measured at an X-ray irradiation angle of 0.22°, is divided by the value obtained by subtracting the value of A when measured at an X-ray irradiation angle of 0.19° from the value of A when measured at an X-ray irradiation angle of 0.22°, to obtain the crystallinity Ci of the intermediate layer.

[0159] <Measurement of uneven distribution of island ratio in resin layer A> The first resin layer (resin layer A) of the adhesive film of Examples 1-7 was measured for the uneven distribution of the island ratio under the following conditions. For the adhesive film of Comparative Example 1, the uneven distribution of the island ratio of the acid-modified polypropylene film was measured in the same manner as in Examples 1-7. The results are shown in Table 1. [Pretreatment conditions] Cut the sample into strips and embed it in thermosetting resin (50℃, 24hr). Ru staining after trimming -Section preparation using an ultramicrotome (using a diamond knife: finishing thickness 80 nm) Os coating (1~3nm)

[0160] [SEM observation conditions] Measurement equipment: Commercially available SEM (e.g. Hitachi High-Technologies Corporation S-4800 TYPE II) Acceleration voltage: 5.0kV Emission current: 20μA WD: 5mm Detector: Upper+HA ·Measurement magnification: 10k times Resolution: 256dpi

[0161] [Image processing conditions] The electron microscope image is subjected to the following image processing to obtain a binary image. For image processing, we can use OpenCV, a Python image processing library. The image processing conditions are listed below. 1. Gaussian filter (kernel size 5px x 5px) 2. Enlarge the measurement image 8 times vertically and horizontally (completion method = CUBIC) 3. Remove noise using the fastNlMeansDenoising function (background color = black, fastNlMeansDenoising function parameters: h = 10, hForColorComponents = 10, templateWindowSize = 7, searchWindowSize = 21) 4. Binarize the image so that bright areas are white and dark areas are black (threshold = Otsu's threshold). 5.Morphological transformation-Open processing (kernel size = 45px x 15px) 6. Noise removal (removal of black areas less than 625px^2) 7. Noise removal (removal of white areas less than 75px^2) 8. Noise removal (removal of black areas less than 10000px^2) 9.Morphological transformation-Open processing (kernel size = 65px x 25px) 10.Morphological transformation-CLOSE processing (kernel size = 25px x 1px) A 504px x 504px area (corresponding to a 1μm x 1μm field of view) is cut out from the obtained binarized image, and the ratio of white areas in that area is defined as W (%). The ratio W of the white areas is calculated by cutting out 40 arbitrary points, The standard deviation of W at 40 locations divided by the average value of W at 40 locations is defined as the uneven distribution degree L of the sea-island structure.

[0162] <Measurement of the degree of orientation of resin layer A> The orientation degree of the first resin layer (resin layer A) of the adhesive film of Examples 1-7 was measured under the following conditions. The orientation degree of the acid-modified polypropylene film of the adhesive film of Comparative Example 1 was measured in the same manner as in Examples 1-7. The results are shown in Table 1. (Measurement conditions) The crystallinity is measured under the following conditions using an X-ray diffraction apparatus (Aichi Synchrotron Light Center, product name BL8S3 beamline). The angle of X-ray irradiation is set to 0.09° with respect to the surface of resin layer A (0°). The measurement range is from the surface of resin layer A to a depth of 5 μm. For example, an R-AXIS is used as the X-ray detector, with a camera length of 500 mm, an X-ray wavelength of 0.92 Å, and an exposure time of 30 seconds.

[0163] (Analysis of resin layer A) Using the X-ray scattering data analysis software FI2D, data from the azimuth angle of 80deg to 100deg is extracted from the spectrum data of the 2D detector and integrated in the azimuth direction to obtain a 1D spectrum showing the intensity value against the diffraction angle 2θ. Furthermore, a straight line passing between the two points of 2θ=4.0deg and 2θ=16.0deg on the 1D spectrum is subtracted as the background. After that, the spectral intensity value A of the amorphous component is defined as the minimum value of the intensity value in the region A: 2θ=8.8deg to 9.8deg, and the crystal peak intensity values ​​P1, P2, P3, and P4 of the four crystal planes are defined as follows. P1: Peak top intensity value of the peak in the 2θ=7.0deg~9.2deg region P2: Peak top intensity value of the peak at 2θ=9.2deg~10.6deg P3: Peak top intensity value of the peak at 2θ=10.6deg~12.0deg P4: Peak top intensity value of the peak at 2θ=12.0deg~14.0deg The degree of crystallinity C is C=(P1+P2+P3+P4) / A The degree of orientation D is defined as D=P2 / P4.

[0164] <Measurement of seal strength (initial) for metal terminals> The seal strength (initial) of the adhesive films of Examples 1-7 and Comparative Example 1 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 0.4 mm was prepared. In addition, each adhesive film for metal terminal obtained in the Examples and Comparative Examples was cut to a length of 45 mm and a width of 10 mm. Next, the adhesive film for metal terminal was placed on the metal terminal to obtain a metal terminal / adhesive film laminate. At this time, the vertical and horizontal directions of the metal terminal were aligned with the length and width directions of the adhesive film for metal terminal, respectively, and the metal terminal and the adhesive film for metal terminal were laminated so that the centers of the metal terminal and the adhesive film for metal terminal were aligned. In addition, the resin layer A of the adhesive film for metal terminal is arranged on the metal terminal side. Next, a polytetrafluoroethylene film (PTFE film, thickness 100 μm) was placed on the adhesive film for metal terminal of the laminate (the surface of the adhesive film for metal terminal was covered with the PTFE film), and the laminate was placed on a press machine heated to 200 ° C (metal terminal was on the hot plate side), and a silicone sponge sheet was placed on the laminate, and the laminate was left at a pressure of 0.25 MPa for 16 seconds to heat-seal the adhesive film to the metal terminal. The laminate after heat-sealing was naturally cooled to 25 ° C. Next, in an environment of 25 ° C, the adhesive film for metal terminal was peeled off from the metal terminal using a Tensilon universal material testing machine (RTG-1210 manufactured by A & D Co., Ltd.). The maximum strength at the time of peeling was taken as the adhesion strength (N / 15 mm) to the metal terminal. The adhesion strength (N / 15 mm) was a conversion value from the adhesion strength (N / 15 mm) measured for the adhesive film for metal terminal with a width of 10 mm. The peel speed was 50 mm / min, the peel angle was 180°, and the chuck distance was 30 mm, and the average value was obtained by measuring three times. The results are shown in Table 1. Note that the treatment of leaving the sample stationary for 16 seconds in a heated and pressurized environment at a temperature of 200°C and a surface pressure of 0.25 MPa is a treatment that simulates the heat and pressure applied in the temporary adhesion process and the main adhesion process.

[0165] <Measurement of seal strength against metal terminals (after immersion in electrolyte)> The seal strength (after immersion in electrolyte) of the adhesive films of Examples 1-7 and Comparative Example 1 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 0.4 mm was prepared. In addition, each adhesive film for metal terminal obtained in the Examples and Comparative Examples was cut to a length of 45 mm and a width of 10 mm. Next, the adhesive film for metal terminal was placed on the metal terminal to obtain a laminate of metal terminal / adhesive film. At this time, the vertical and horizontal directions of the metal terminal were aligned with the length and width directions of the adhesive film for metal terminal, respectively, and the metal terminal and the adhesive film for metal terminal were laminated so that the centers of the metal terminal and the adhesive film for metal terminal were aligned. In addition, the resin layer A of the adhesive film for metal terminal is arranged on the metal terminal side. Next, a polytetrafluoroethylene film (PTFE film, 100 μm thick) was placed on the adhesive film for metal terminal of the laminate (the surface of the adhesive film for metal terminal was covered with the PTFE film), and the laminate was placed on a press machine heated to 200°C (the metal terminal was on the hot plate side), and a silicone sponge sheet was placed on top, and the laminate was left standing for 16 seconds at a pressure of 0.25 MPa to heat-seal the adhesive film to the metal terminal. The laminate after heat-sealing was naturally cooled to 25°C. Next, the obtained laminate was placed in a 100 mL plastic bottle, and 100 g of electrolyte (EC (ethylene carbonate) / DMC (dimethyl carbonate) / DEC (diethyl carbonate) = 1: 1: 1) + 1000 ppm of pure water was mixed therein and tightly sealed. The sealed container was placed in an oven at 85°C, and after 24 hours, it was taken out, the electrolyte was washed away with water, and the obtained laminate was left standing for 30 minutes to dry naturally. Next, in an environment of 25°C, the adhesive film for metal terminals was peeled off from the metal terminal using a Tensilon universal material testing machine (RTG-1210 manufactured by A&D). The maximum strength at the time of peeling was taken as the adhesion strength to the metal terminal (N / 15mm). The peel speed was 50mm / min, the peel angle was 180°, and the chuck distance was 30mm, and the average value was taken from three measurements. The results are shown in Table 1. The process of leaving the film for 16 seconds in a heated and pressurized environment at a temperature of 200°C and a surface pressure of 0.25MPa is a process that simulates the heat and pressure applied in the temporary adhesion process and the main adhesion process described above.

[0166] <Ten-point average roughness of the outermost layer surface of adhesive film> The ten-point average roughness was measured for the surface of the resin layer A of each adhesive film for metal terminal obtained in Examples 1-7 and Comparative Example 1 by a method conforming to the provisions of JIS B0601:1994. A small surface roughness tester SURFTEST SJ-210 manufactured by Mitutoyo was used for the measurement, and the measurement conditions were a measurement speed of 0.5 mm and a range of AUTO. As a result, the ten-point average roughness was 0.34 μm in Example 1, 0.90 μm in Example 2, 0.26 μm in Example 3, 0.24 μm in Example 4, 0.35 μm in Example 5, 0.35 μm in Example 6, 0.35 μm in Example 7, and 0.40 μm in Comparative Example 1.

[0167] <Measurement of heat shrinkage rate (%)> The adhesive film for metal terminals was cut into a size of 110 mm (MD) x 10 mm (TD) width to prepare a test piece. Next, the length M (mm) of the test piece was measured with a metal ruler. Next, the end (about 10 mm) in the longitudinal direction of the test piece was fixed to a wire mesh with tape, and the test piece was hung from the wire mesh. In this state, the test piece was placed in an oven heated to 190°C for 120 seconds, and then the test piece was taken out together with the wire mesh and naturally cooled in a room temperature (25°C) environment. Next, the length N (mm) of the test piece naturally cooled to room temperature was measured with a metal ruler. The thermal shrinkage rate of the adhesive film for metal terminals was calculated using the following formula. Heat shrinkage rate (%) = (1-(length N / length M)) x 100

[0168] [Table 1]

[0169] As described above, the present disclosure provides the inventions of the following aspects. Item 1. An adhesive film for a metal terminal, which is interposed between a metal terminal electrically connected to an electrode of an electricity storage device element and an exterior material for an electricity storage device that encapsulates the electricity storage device element, The resin layer A forming at least one surface of the adhesive film for metal terminal contains an acid-modified polyolefin, An adhesive film for metal terminal, wherein the resin layer A has a crystallinity of 3 or more and 18 or less, as measured under the following conditions using an X-ray diffraction device. (Measurement conditions) The angle of X-ray irradiation is set to 0.09° with respect to the surface of the resin layer A (0°). The measurement range is from the surface of the resin layer A to a depth of 5 μm. The camera length of the X-ray detector is 500 mm, the X-ray wavelength is 0.92 Å, and the exposure time is 30 seconds. Item 2. The adhesive film for a metal terminal according to item 1, wherein when the resin layer A is analyzed by infrared spectroscopy, a peak derived from maleic anhydride is detected. Item 3. The adhesive film for metal terminal according to item 1 or 2, wherein the resin layer A has an island ratio of a sea-island structure with a degree of uneven distribution of 1.00 or less. Item 4. The adhesive film for metal terminal according to item 1 or 2, wherein the resin layer A has a degree of orientation of 0.5 or more. Item 5. The adhesive film for a metal terminal according to item 1 or 2, wherein the adhesive film for a metal terminal is formed from a polyolefin resin. Item 6. The adhesive film for metal terminal is composed of a laminate including, in this order, a first resin layer disposed on the metal terminal side, an intermediate layer, and a second resin layer disposed on the exterior material side for the electric storage device; Item 3. The adhesive film for metal terminal according to item 1 or 2, wherein the first resin layer is the resin layer A. Item 7. The adhesive film for metal terminal according to item 6, wherein the intermediate layer has a crystallinity of 3.0 or more as measured under the following conditions using an X-ray diffraction apparatus: The X-ray irradiation angles are 0.19° and 0.22° relative to the surface of the intermediate layer (0°). The camera length of the X-ray detector is 500 mm, the X-ray wavelength is 0.92 Å, and the exposure time is 30 seconds. Item 8. A method for producing an adhesive film for a metal terminal, which is interposed between a metal terminal electrically connected to an electrode of an electricity storage device element and an exterior material for an electricity storage device that encapsulates the electricity storage device element, comprising: The resin layer A forming at least one surface of the adhesive film for metal terminal contains an acid-modified polyolefin, The method for producing an adhesive film for a metal terminal, wherein the resin layer A has a crystallinity of 3 or more and 18 or less, as measured under the following conditions using an X-ray diffraction device. (Measurement conditions) The angle of X-ray irradiation is set to 0.09° with respect to the surface of the resin layer A (0°). The measurement range is from the surface of the resin layer A to a depth of 5 μm. The camera length of the X-ray detector is 500 mm, the X-ray wavelength is 0.92 Å, and the exposure time is 30 seconds. Item 9. A metal terminal with an adhesive film for a metal terminal, comprising the adhesive film for a metal terminal according to any one of items 1 to 7 attached to a metal terminal. Item 10. An electricity storage device including at least an electricity storage device element having a positive electrode, a negative electrode, and an electrolyte, an exterior material for an electricity storage device that seals the electricity storage device element, and metal terminals that are electrically connected to the positive electrode and the negative electrode, respectively, and protrude to the outside of the exterior material for an electricity storage device, 8. An electricity storage device, comprising the adhesive film for a metal terminal according to any one of items 1 to 7 interposed between the metal terminal and the exterior material for an electricity storage device. Item 11. A method for manufacturing an electricity storage device including at least an electricity storage device element including a positive electrode, a negative electrode, and an electrolyte, an exterior material for an electricity storage device that seals the electricity storage device element, and metal terminals that are electrically connected to the positive electrode and the negative electrode, respectively, and protrude to the outside of the exterior material for an electricity storage device, A method for producing an electricity storage device, comprising a step of interposing the adhesive film for metal terminal according to any one of items 1 to 7 between the metal terminal and the exterior material for an electricity storage device, and sealing the electricity storage device element with the exterior material for an electricity storage device. Item 12. An exterior material for an electricity storage device for use in an electricity storage device, The electricity storage device includes at least an electricity storage device element having a positive electrode, a negative electrode, and an electrolyte, the electricity storage device exterior material sealing the electricity storage device element, and the metal terminals electrically connected to the positive electrode and the negative electrode, respectively, and protruding to the outside of the electricity storage device exterior material, and an adhesive film for metal terminals is interposed between the metal terminals and the electricity storage device exterior material, The adhesive film for a metal terminal is the adhesive film for a metal terminal according to any one of items 1 to 7, The electrical storage device packaging material is composed of a laminate including at least a base layer, a barrier layer, and a heat-sealable resin layer. Item 13. A kit comprising an exterior material for an electricity storage device for use in an electricity storage device and the adhesive film for a metal terminal according to any one of items 1 to 7, The electricity storage device includes at least an electricity storage device element having a positive electrode, a negative electrode, and an electrolyte, the electricity storage device exterior material sealing the electricity storage device element, and the metal terminals electrically connected to the positive electrode and the negative electrode, respectively, and protruding to the outside of the electricity storage device exterior material, The kit is used such that, when used, the adhesive film for a metal terminal is interposed between the metal terminal and the exterior material for an electricity storage device. [Explanation of symbols]

[0170] 1. Adhesive film for metal terminals 2 metal terminals 3. Exterior materials for energy storage devices 3a Periphery of exterior material for power storage device 4. Energy storage device elements 10. Energy storage devices 11 Middle Class 12a 1st resin layer 12b 2nd resin layer 31 Base material layer 32 Adhesive layer 33 Barrier Layer 34 Adhesive layer 35. Thermally fusible resin layer

Claims

1. An adhesive film for metal terminals, which is interposed between a metal terminal electrically connected to an electrode of an electricity storage device element and an exterior material for an electricity storage device that seals the electricity storage device element, the resin layer A forming at least one surface of the adhesive film for metal terminal contains an acid-modified polyolefin; The resin layer A has an island portion ratio unevenness of 1.00 or less in a sea-island structure, the sea portion of the sea-island structure is formed of an acid-modified polypropylene component, and the island portion is formed of a polyethylene component; The electron microscope image of the sea-island structure is subjected to binarization image processing so that bright areas are white and dark areas are black, and the ratio of white areas at any 40 points is W (%), and the standard deviation of the 40 points is divided by the average value to determine the uneven distribution of the island ratio. An adhesive film for a metal terminal, wherein the resin layer A has a crystallinity of 3 or more and 18 or less as measured under the following conditions using an X-ray diffraction device. (Measurement conditions) The angle of X-ray irradiation is set to 0.09° with respect to the surface of the resin layer A (0°). The measurement range is from the surface of the resin layer A to a depth of 5 μm. The camera length of the X-ray detector is 500 mm, the X-ray wavelength is 0.92 Å, and the exposure time is 30 seconds. The crystallinity is determined by defining the X-ray diffraction spectrum intensity value A as the minimum intensity value in the region of 2θ = 8.8 deg to 9.8 deg, defining the crystal peak intensity values ​​P1, P2, P3, and P4 of the four crystal planes as follows, and calculating the crystallinity C = (P1 + P2 + P3 + P4) / A. P1: Intensity value of the peak top of the peak in the region of 2θ = 7.0 deg to 9.2 deg P2: Peak top intensity value of the peak at 2θ = 9.2 deg to 10.6 deg P3: Peak top intensity value of the peak at 2θ = 10.6 deg to 12.0 deg P4: Peak top intensity value of the peak at 2θ = 12.0 deg to 14.0 deg

2. An adhesive film for metal terminals as described in claim 1, wherein when the resin layer A is analyzed by infrared spectroscopy, a peak derived from maleic anhydride is detected.

3. The resin layer A has an orientation degree of 0.5 or more, 3. The adhesive film for a metal terminal according to claim 1, wherein the degree of orientation is defined by P2 / P4, where P2 and P4 are crystal peak intensity values.

4. An adhesive film for metal terminals as described in claim 1 or 2, wherein the adhesive film for metal terminals is formed from a polyolefin resin.

5. The adhesive film for metal terminals is composed of a laminate having, in this order, a first resin layer arranged on the metal terminal side, an intermediate layer, and a second resin layer arranged on the exterior material side for the electricity storage device; The adhesive film for a metal terminal according to claim 1 or 2, wherein the first resin layer is the resin layer A.

6. An adhesive film for metal terminals as described in claim 5, wherein the crystallinity of the intermediate layer measured using an X-ray diffraction device under the following conditions is 3.0 or more. The X-ray irradiation angles are set to 0.19° and 0.22° relative to the surface of the intermediate layer (0°). The camera length of the X-ray detector is 500 mm, the X-ray wavelength is 0.92 Å, and the exposure time is 30 seconds.

7. A method for producing an adhesive film for a metal terminal, which is interposed between a metal terminal electrically connected to an electrode of an electricity storage device element and an exterior material for an electricity storage device that encapsulates the electricity storage device element, comprising: The resin layer A has an island portion ratio unevenness of 1.00 or less in a sea-island structure, the sea portion of the sea-island structure is formed of an acid-modified polypropylene component, and the island portion is formed of a polyethylene component; The electron microscope image of the sea-island structure is subjected to binarization image processing so that bright areas are white and dark areas are black, and the ratio of white areas at any 40 points is W (%), and the standard deviation of the 40 points is divided by the average value to determine the uneven distribution of the island ratio. the resin layer A forming at least one surface of the adhesive film for metal terminal contains an acid-modified polyolefin; A method for producing an adhesive film for a metal terminal, wherein the resin layer A has a crystallinity of 3 or more and 18 or less as measured under the following conditions using an X-ray diffraction device. (Measurement conditions) The angle of X-ray irradiation is set to 0.09° with respect to the surface of the resin layer A (0°). The measurement range is from the surface of the resin layer A to a depth of 5 μm. The camera length of the X-ray detector is 500 mm, the X-ray wavelength is 0.92 Å, and the exposure time is 30 seconds. The crystallinity is determined by defining the X-ray diffraction spectrum intensity value A as the minimum intensity value in the region of 2θ = 8.8 deg to 9.8 deg, defining the crystal peak intensity values ​​P1, P2, P3, and P4 of the four crystal planes as follows, and calculating the crystallinity C = (P1 + P2 + P3 + P4) / A. P1: Intensity value of the peak top of the peak in the region of 2θ = 7.0 deg to 9.2 deg P2: Peak top intensity value of the peak at 2θ = 9.2 deg to 10.6 deg P3: Peak top intensity value of the peak at 2θ = 10.6 deg to 12.0 deg P4: Peak top intensity value of the peak at 2θ = 12.0 deg to 14.0 deg

8. A metal terminal with an adhesive film for metal terminals, comprising an adhesive film for metal terminals as described in claim 1 or 2 attached to a metal terminal.

9. An electricity storage device comprising at least an electricity storage device element having a positive electrode, a negative electrode, and an electrolyte, an exterior material for an electricity storage device that seals the electricity storage device element, and metal terminals that are electrically connected to the positive electrode and the negative electrode, respectively, and protrude outside the exterior material for an electricity storage device, An electricity storage device, comprising the adhesive film for metal terminals according to claim 1 or 2 interposed between the metal terminals and the exterior material for electricity storage devices.

10. A method for manufacturing an electricity storage device comprising at least an electricity storage device element having a positive electrode, a negative electrode, and an electrolyte, an exterior material for the electricity storage device that seals the electricity storage device element, and metal terminals that are electrically connected to the positive electrode and the negative electrode, respectively, and protrude outside the exterior material for the electricity storage device, 3. A method for manufacturing an electricity storage device, comprising a step of interposing the adhesive film for metal terminals according to claim 1 or 2 between the metal terminals and the exterior material for an electricity storage device, and sealing the electricity storage device elements with the exterior material for an electricity storage device.

11. An exterior material for an electricity storage device for use in an electricity storage device, comprising: the electricity storage device includes at least an electricity storage device element having a positive electrode, a negative electrode, and an electrolyte, the electricity storage device exterior material sealing the electricity storage device element, and the metal terminals electrically connected to the positive electrode and the negative electrode, respectively, and protruding to the outside of the electricity storage device exterior material, and an adhesive film for metal terminals is interposed between the metal terminals and the electricity storage device exterior material, The adhesive film for a metal terminal is the adhesive film for a metal terminal according to claim 1 or 2, The packaging material for an electricity storage device is composed of a laminate including at least a base layer, a barrier layer, and a heat-sealable resin layer.

12. A kit comprising an exterior material for an electricity storage device for use in an electricity storage device and the adhesive film for metal terminals according to claim 1 or 2, the electricity storage device includes at least an electricity storage device element including a positive electrode, a negative electrode, and an electrolyte, the electricity storage device exterior material sealing the electricity storage device element, and the metal terminals electrically connected to the positive electrode and the negative electrode, respectively, and protruding to the outside of the electricity storage device exterior material; The kit is used such that, when used, the adhesive film for a metal terminal is interposed between the metal terminal and the exterior material for an electricity storage device.

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