Adhesive film for power storage devices

Abstract

Provided is an adhesive film for power storage devices, which exhibits excellent water vapor barrier property and is capable of discharging gas generated inside the power storage device.　This adhesive film is to be bonded to an exterior material of a power storage device. The adhesive film is composed of a laminate that at least comprises a base material layer and an adhesive layer. The base material layer contains a fluorine resin.

Description

Adhesive film for power storage devices

[0001] The present disclosure relates to an adhesive film for an electricity storage device.

[0002] Various types of electricity storage devices have been developed to date, and in all of these devices, exterior materials are essential components for sealing electricity storage device elements such as electrodes and electrolytes.

[0003] Conventionally, metal exterior materials have been widely used as exterior materials.

[0004] Furthermore, in recent years, a laminate sheet in which a base material layer, a barrier layer, and a heat-sealable resin layer are laminated in this order has been proposed as an exterior material that can be easily processed into a variety of shapes and can be made thinner and lighter. When such a laminate film-like exterior material is used, the heat-sealable resin layers located in the innermost layers of the exterior material are placed opposite each other, and the peripheral edge of the exterior material is heat-sealed to seal the electricity storage device element in the exterior material.

[0005] JP 2016-31934 A JP 2010-153841 A

[0006] For example, Patent Document 1 discloses a battery in which a battery element is housed in a pouch. The pouch has a valve structure with a check valve attached to a heat-sealed portion formed along its periphery. The check valve is configured to operate and release gas when the internal pressure of the pouch rises above a certain level.

[0007] Furthermore, Patent Document 2 discloses a battery in which a battery element is housed in a box-shaped laminated container. This laminated container has a flange-shaped heat-sealed portion formed along its periphery, which has a portion (hereinafter referred to as an easy-peel portion) that is easier to peel than other portions. The easy-peel portion peels when the internal pressure of the laminated container rises above a certain level, and gas is released through a hole formed in the center of the easy-peel portion. Unlike the check valve in Patent Document 1, the easy-peel portion is a breakable valve that does not return to its original state once peeled.

[0008] A primary object of the present disclosure is to provide an adhesive film for an electricity storage device that has excellent water vapor barrier properties and is capable of discharging gas generated inside the electricity storage device.

[0009] The inventors of the present disclosure have conducted extensive research to solve the above-mentioned problems, and as a result have found that by using a fluororesin for the base layer of an adhesive film composed of a laminate including at least a base layer and an adhesive layer, and by adhering the adhesive film to the exterior material of an electricity storage device, the adhesive film has excellent water vapor barrier properties and can also discharge gas (specifically, carbon dioxide) generated inside the electricity storage device.

[0010] More specifically, the inventors of the present disclosure have discovered that by adhering the adhesive film to the surface of the exterior material of an electricity storage device (at least one surface of the exterior material, for example, the surface on the base material layer side and / or the surface on the heat-sealable resin layer side of the exterior material) so as to block a communication portion provided in the exterior material of the electricity storage device, thereby allowing gas generated inside the electricity storage device to be discharged through the communication portion, and by using the adhesive layer of the adhesive film adhered to the surface of the electricity storage device, the adhesive film can exhibit excellent water vapor barrier properties while also being able to suitably discharge gas generated inside the electricity storage device.

[0011] The inventors of the present disclosure have also discovered that by arranging the adhesive film so that it is interposed between the welded parts of the exterior material of the electricity storage device, allowing gas generated inside the electricity storage device to be discharged, and then adhering the adhesive film to the welded parts of the exterior material so that gas can permeate in the thickness direction of the adhesive film, thereby discharging gas generated inside the electricity storage device, it is possible to exhibit excellent water vapor barrier properties while also suitably discharging gas generated inside the electricity storage device.

[0012] The present disclosure was completed through further investigation based on these findings.

[0013] That is, the present disclosure provides the following invention: An adhesive film that is adhered to an exterior material of an electricity storage device and used to release gas generated inside the electricity storage device, the adhesive film being composed of a laminate including at least a base layer and an adhesive layer, and the base layer containing a fluororesin.

[0014] According to the present disclosure, it is possible to provide an adhesive film for an electricity storage device that has excellent water vapor barrier properties and is capable of discharging gas generated inside the electricity storage device.

[0015] 8 is a schematic diagram of an example in which an adhesive film of the present disclosure is applied to the surface of an exterior material (prismatic metal can) of an electricity storage device. FIG. 9 is a schematic diagram of an example in which an adhesive film of the present disclosure is applied to the surface of an exterior material (prismatic metal can) of an electricity storage device. FIG. 10 is a schematic diagram of an example in which an adhesive film of the present disclosure is applied to the surface of an exterior material (cylindrical metal can) of an electricity storage device. FIG. 11 is a schematic diagram of an example in which an adhesive film of the present disclosure is applied to the surface of an exterior material (laminate film) of an electricity storage device. FIG. 12 is a schematic diagram of an example in which an adhesive film of the present disclosure is applied to the surface of an exterior material (laminate film) of an electricity storage device. FIG. 13 is a schematic cross-sectional view taken along line A-A' in FIG. 7. FIG. 14 is an enlarged view of region IX in FIG. 15. FIG. 16 is a schematic diagram of an example in which an adhesive film of the present disclosure is applied to a welded portion of an exterior material (laminate film) of an electricity storage device. 10 is a schematic cross-sectional view taken along line A-A' in FIG. 10. It is an enlarged view of region XII in FIG. 11. It is a schematic cross-sectional view of an adhesive film in which only the end portions are heat-sealed in a folded-back state with two adhesive films superposed on one another. It is a schematic view of an example in which an adhesive film of the present disclosure is applied to a welded portion of an exterior material (laminated film) of an electricity storage device. It is a schematic cross-sectional view taken along line A-A' in FIG. 14. It is an enlarged view of region XVI in FIG. 15. It is a schematic view of an example in which an adhesive film of the present disclosure is applied to a welded portion of an exterior material (laminated film) of an electricity storage device. It is a schematic cross-sectional view taken along line A-A' in FIG. 17. It is an enlarged view of region XIX in FIG. 18. It is an example of a schematic cross-sectional view of an adhesive film of the present disclosure. It is an example of a schematic cross-sectional view of an adhesive film of the present disclosure. It is a schematic cross-sectional view of an exterior material made of a laminate film.

[0016] The adhesive film of the present disclosure is an adhesive film that is adhered to the exterior material of an electricity storage device and used to release gas generated inside the electricity storage device, and is composed of a laminate including at least a base material layer and an adhesive layer, and is characterized in that the base material layer contains a fluororesin. By having this configuration, the adhesive film of the present disclosure has excellent water vapor barrier properties and can release gas generated inside the electricity storage device. By adhering the adhesive film of the present disclosure to the exterior material of an electricity storage device, it can be suitably used as an impermeable gas venting film.

[0017] The adhesive film of the present disclosure will be described in detail below with reference to FIGS.

[0018] In this specification, when referring to a numerical range, a numerical range indicated with "to" means "greater than or equal to" or "less than or equal to." For example, the notation 2 to 15 mm means 2 mm or greater and 15 mm or less. In the numerical ranges described in stages in this disclosure, the upper or lower limit value described in a certain numerical range may be replaced with the upper or lower limit value of another numerical range described in stages. Furthermore, separately described upper and lower limits, upper and lower limits, or lower and lower limits may each be combined to form a numerical range. Furthermore, in the numerical ranges described in this disclosure, the upper or lower limit value described in a certain numerical range may be replaced with a value shown in the examples.

[0019] Another method for confirming the MD of an adhesive film is to observe a cross section of the adhesive film (e.g., a cross section of an acid-modified polyolefin layer or a polyolefin layer) using an electron microscope to confirm the sea-island structure. In this method, the direction parallel to the cross section in which the average diameter of the island shapes in the direction perpendicular to the thickness direction of the adhesive film is the largest can be determined as the MD. Specifically, the sea-island structure is confirmed by observing, using an electron microscope, a cross section of the adhesive film in the longitudinal direction and each cross section at an angle of 10 degrees from the direction parallel to the cross section in the longitudinal direction up to the direction perpendicular to the cross section in the longitudinal direction (a total of 10 cross sections). Next, the shape of each individual island is observed in each cross section. For each island shape, the linear distance connecting the leftmost end in the direction perpendicular to the thickness direction of the adhesive film to the rightmost end in the vertical direction is defined as the diameter y. For each cross section, the diameter y of the top 20 island shapes in order of largest diameter y is calculated. The direction parallel to the cross section in which the average diameter y of the island shapes is largest is determined as the MD. Alternatively, for example, the adhesive film may be left in an environment of 150° C. for 2 minutes, and the thermal shrinkage rate measured, and the film with a larger shrinkage rate may be determined as MD.

[0020] The adhesive film of the present disclosure is an adhesive film used in an electricity storage device. First, how the adhesive film of the present disclosure is used in an electricity storage device will be described in detail, and then the laminate structure of the adhesive film, the characteristics and physical properties of the resins used in each layer, etc. will be described in detail.

[0021] The adhesive film of the present disclosure is adhered to the exterior material of an electricity storage device and is used to release gas generated inside the electricity storage device.

[0022] In a specific example of how the adhesive film of the present disclosure is used in an electricity storage device, the adhesive film of the present disclosure is adhered to the surface of the exterior material of the electricity storage device (at least one surface of the exterior material, for example, the surface on the base material layer side and / or the surface on the heat-sealable resin layer side of the exterior material) so as to block a communicating portion provided in the exterior material of the electricity storage device, and is used to discharge gas generated inside the electricity storage device through the communicating portion. In the adhesive film of the present disclosure, the adhesive layer is adhered to the surface of the exterior material of the electricity storage device, so that the adhesive film is adhered to the surface of the exterior material so as to block the communicating portion provided in the exterior material of the electricity storage device. That is, in the adhesive film of the present disclosure, at least one surface is preferably composed of an adhesive layer.

[0023] For example, the adhesive film 1 of the present disclosure shown in the schematic diagrams of Figures 1 to 9 is adhered to the surface of an exterior material 3 of an electricity storage device 10 so as to block a communication portion H provided in the exterior material 3. Gas generated inside the electricity storage device 10 (electricity storage device element 4) permeates the adhesive film 1 and is discharged from the communication portion H. In other words, the communication portion H is a communication portion that connects the electricity storage device element 4 to the outside, and the adhesive film 1 prevents moisture from penetrating from outside the electricity storage device 10, and allows gas generated inside the electricity storage device 10 (electricity storage device element 4) to be discharged to the outside.

[0024] 1 and 2 illustrate an embodiment in which the exterior material 3 of the electricity storage device 10 is formed of a rectangular metal can. Also, Figs. 3 and 4 illustrate an embodiment in which the exterior material 3 of the electricity storage device 10 is formed of a cylindrical metal can.

[0025] 1 to 4, the surface of the exterior packaging material 3 to which the adhesive film 1 is adhered is made of metal. That is, when the adhesive film 1 is applied to an exterior packaging material 3 made of a metal can, the adhesive layer of the adhesive film 1 can be made of a resin that is water-impermeable and gas-permeable and has adhesive properties to the metal that constitutes the outer surface of the exterior packaging material 3.

[0026] Figures 5 to 9 illustrate an embodiment in which the exterior material 3 of the electricity storage device 10 is composed of a laminate (laminated film) having at least a base material layer 31, a barrier layer 33, and a heat-sealable resin layer 35 in this order.

[0027] 5 to 9, the surface of the exterior packaging material 3 to which the adhesive film 1 is adhered is made of resin. That is, when the adhesive film 1 is applied to an exterior packaging material 3 made of a laminated film, the adhesive layer of the adhesive film 1 can be made of a resin that is water-impermeable and gas-permeable and has adhesive properties to the resin that constitutes the outer surface of the exterior packaging material.

[0028] The shape (shape in plan view) of the communication portion H provided in the exterior material 3 is not particularly limited. For example, Figures 1, 3, and 5 show a configuration in which the communication portion H is circular, while Figures 2, 4, and 6 show a configuration in which the communication portion H is made up of multiple rectangular shapes with slits.

[0029] Furthermore, the location where the communication portion H is provided is not particularly limited, and the communication portion H can be provided on the bottom surface, side surface, or welded portion of the electricity storage device 10. For example, FIGS. 1 to 6 illustrate an embodiment in which the communication portion H is provided on the bottom surface (which can also be referred to as the upper surface, bottom surface, or top surface) of the electricity storage device 10. For example, FIGS. 7 to 9 illustrate an embodiment in which the communication portion H is provided in a welded portion of the electricity storage device 10 (a welded portion between the heat-sealable resin layers 35 formed on the peripheral portion 3 a of the exterior material 3, which will be described later). When the communication portion H is provided in the welded portion of the electricity storage device 10 as shown in FIGS. 7 to 9 , an unwelded portion can be formed in a part of the welded portion between the heat-sealable resin layers 35 formed on the peripheral portion 3 a of the exterior material 3, and this portion can be used as the communication portion H.

[0030] Gas generated inside the electricity storage device 10 reaches the adhesive film 1 through the communication parts H, and the adhesive film 1 is adhered to the surface of the electricity storage device 10 so that the gas permeates in the thickness direction of the adhesive film 1. As described below, the gas can permeate the adhesive film 1 in the thickness direction of the adhesive film 1 because the distance that the gas must permeate is short. On the other hand, the gas is less likely to permeate in the direction perpendicular to the thickness direction of the adhesive film 1 because the distance that the gas must permeate is long. Therefore, it is important to adhere the adhesive film 1 of the present disclosure to the surface of the exterior material 3 so as to block the communication parts H provided in the exterior material 3 of the electricity storage device 10, thereby allowing the gas to permeate in the thickness direction of the adhesive film 1.

[0031] 7 to 9, the communicating portion H is provided in the welded portion of the electricity storage device 10 (the welded portion of the heat-sealable resin layer 35 formed on the peripheral edge 3a of the exterior material 3, which will be described later). An adhesive film 1 is attached to the communicating portion H provided in part of the welded portion of the peripheral edge 3a of the exterior material 3, and as shown in the enlarged view of Fig. 9, gas generated inside the electricity storage device 10 is permeated in the thickness direction of the adhesive film 1 and discharged to the outside. It is also possible to form a portion of the exterior material 3 where the heat-sealable resin layer 35 is not provided, and use this portion as the communicating portion H.

[0032] In another specific example of how the adhesive film of the present disclosure is used in an electricity storage device, the adhesive film of the present disclosure is disposed so as to be interposed between the welded parts of the exterior material of the electricity storage device, and is used to discharge gas generated inside the electricity storage device. In the adhesive film of the present disclosure, the adhesive layer of the adhesive film is adhered to the welded parts of the exterior material, and gas permeates through the adhesive film in the thickness direction, thereby discharging gas generated inside the electricity storage device to the outside. In the adhesive film of the present disclosure, in order for gas to permeate through the adhesive film in the thickness direction, the adhesive film is disposed so as to be interposed between the welded parts of the exterior material, with the adhesive film blocking the openings of the communication parts of the exterior material in the thickness direction.

[0033] For example, as shown in the schematic diagrams of Figures 10 to 12 and 14 to 19, the adhesive film 1 of the present disclosure is disposed so as to be interposed between the welded parts of the exterior material 3 of the electricity storage device 10. Gas generated inside the electricity storage device 10 (electricity storage device elements 4) is discharged through the adhesive film 1. In other words, the adhesive film 1 disposed between the welded parts serves to block the communication parts connecting the electricity storage device elements 4 to the outside, and the adhesive film 1 prevents moisture from penetrating from outside the electricity storage device 10, and gas generated inside the electricity storage device 10 (electricity storage device elements 4) is discharged to the outside.

[0034] 10 to 12 and 14 to 19, the adhesive film 1 is folded back and sandwiched between the welded portions of the exterior material 3 of the electricity storage device 10. By folding the adhesive film 1 so that the adhesive layer of the adhesive film 1 faces outward and the base material layer faces inward, the outer adhesive layer and the heat-sealable resin layer 35 of the exterior material 3 can be bonded together.

[0035] In addition to folding the adhesive film 1, the adhesive film 1 to be placed between the welded portions may be folded back by, for example, folding back the ends of two adhesive films in a state where two adhesive films are stacked so that the adhesive layers of the two adhesive films face each other, and heat-sealing the adhesive layers (at the position of the heat-sealed portion HS in FIG. 13 ) to form the folded back shape, as shown in the schematic diagram of Fig. 13. In this case, the heat-sealing of the two adhesive films 1 may be performed before the adhesive film 1 is placed between the welded portions, or may be performed by placing the two adhesive films in a stacked state between the packaging material 3 when forming the welded portion of the packaging material 3, and heat-sealing the ends of the adhesive film 1 simultaneously with the formation of the welded portion. In addition, as shown in Figure 16, for example, if the area where two adhesive films 1 are heat-sealed becomes large, it becomes difficult for gas to permeate through the heat-sealed portion. Therefore, it is desirable to design the adhesive film 1 so that a part of the adhesive film 1 protrudes from the welded portion of the exterior material 3, as shown in Figures 14 to 16 described below, and to place the adhesive film 1 at the welded portion of the exterior material 3 so that the gas permeates in the thickness direction of the adhesive film and is discharged.

[0036] Figures 10 to 12 and 14 to 19 illustrate an embodiment in which the exterior material 3 of the energy storage device 10 is composed of a laminate (laminated film) having at least a base material layer 31, a barrier layer 33, and a heat-sealable resin layer 35 in this order.

[0037] 10 to 12 and 14 to 19, the welded portion formed on the peripheral portion 3a of the exterior packaging material 3 is made of resin (for example, a heat-sealable resin layer 35 of the exterior packaging material 3 described below). That is, when the adhesive film 1 is applied to an exterior packaging material 3 formed of a laminated film, the adhesive film 1 can be made of a resin that is water-impermeable and gas-permeable and has adhesiveness to the resin that forms the innermost layer of the exterior packaging material (that is, a heat-sealable resin layer 35 of the exterior packaging material 3 described below).

[0038] As shown in Figures 14 to 16, the adhesive film 1 can also be disposed at the welded portion of the exterior packaging material 3 so that a part of the adhesive film 1 protrudes from the welded portion of the exterior packaging material 3. In the schematic views of Figures 14 to 16, the part of the adhesive film 1 protruding from the welded portion has its periphery heat-sealed to form a bag shape, and as shown in the schematic view of Figure 16, the adhesive film 1 is disposed so that gas can pass through from the thickness direction. Note that Figures 14 to 16 show an example in which two adhesive films 1 are laminated and three sides (the side on the x1 side, the side on the x2 side, and the side on the z1 side in Figure 14) of the part of the adhesive film 1 protruding from the welded portion are heat-sealed, but one adhesive film 1 may be folded back and two sides (the side on the x1 side and the x2 side in Figure 14) may be heat-sealed (the z1 side is the folded portion).

[0039] 17 to 19, a communication part H where the surface of the adhesive film 1 is exposed can be provided in the welded part of the exterior material 3. Gas can also be discharged through the communication part H. As described above, the shape of the communication part H (shape in plan view) is not particularly limited, and for example, although FIG. 17 illustrates a configuration in which the communication part H is made up of a plurality of rectangular slits, it may also be a circular shape, etc.

[0040] As described above, the distance that gas must permeate in the thickness direction of the adhesive film 1 is short, and therefore the gas can permeate the adhesive film 1. On the other hand, the distance that gas must permeate in the direction perpendicular to the thickness direction of the adhesive film 1 is long, and therefore the gas is less likely to permeate. Therefore, it is important to allow the gas to permeate in the thickness direction of the adhesive film 1.

[0041] Next, the laminate structure, resin, physical properties, etc. of the adhesive film of the present disclosure will be described in detail.

[0042] The adhesive film 1 of the present disclosure is composed of a laminate including at least a base layer and an adhesive layer. Furthermore, the adhesive film 1 of the present disclosure has a function of allowing gas generated inside the electricity storage device to permeate in the thickness direction of the adhesive film 1. The adhesive film 1 also has water impermeability.

[0043] In other words, the adhesive film 1 of the present disclosure as a whole must be permeable to gas generated inside the energy storage device (gas can pass through in the thickness direction of the adhesive film 1), and must also be non-permeable so as to prevent moisture from penetrating from the external environment of the energy storage device.

[0044] <Water Vapor Permeability> From the viewpoint of suitably exhibiting the effects of the present invention, the adhesive film 1 of the present disclosure preferably has a water vapor permeability measured by the following measurement method of about 25 g / m 2 / day or less, more preferably about 15 g / m 2 / day or less, more preferably about 10 g / m 2 / day or less, more preferably about 5 g / m 2 / day or less, more preferably about 0 g / m 2 The water vapor permeability of the adhesive film 1 was measured as follows.

[0045] The water vapor permeability is measured under the following measurement conditions in accordance with the gas chromatography method specified in JIS K7129-4:2019. (Measurement conditions) Sheet shape: 80 mm diameter circle Differential pressure gas: Measured using a water vapor permeability measuring device Test conditions: 60°C, 90% RH Permeation direction: Permeation from the adhesive layer side constituting one surface of the adhesive film Number of measurements: 1

[0046] <Carbon dioxide permeability> In order to suitably exert the effects of the present invention, the adhesive film 1 of the present disclosure preferably has a carbon dioxide permeability measured by the following measurement method of 5000 cc / m 2 / day or more, more preferably 10,000cc / m 2 / day or more, more preferably 12,000 cc / m 2 / day or more, more preferably 13,000 cc / m 2 The upper limit of the carbon dioxide permeability of the adhesive film 1 of the present disclosure is, for example, 300,000 cc / m 2 The carbon dioxide permeability of the adhesive film 1 is measured by the following method.

[0047] Carbon dioxide permeability is measured under the following conditions in accordance with the provisions of Appendix 2 of JIS K7126-1:2006. (Measurement conditions) Sheet shape: 80 mm diameter circle Differential pressure gas: Measured using a water vapor permeability measuring device Test conditions: 60°C, 0% RH Permeation direction: Permeation from the base layer side that constitutes one surface of the adhesive film Number of measurements: 1

[0048] <Tensile strength> The adhesive film of the present disclosure has a tensile strength in the MD direction measured in accordance with the provisions of JIS K6251:2017 under the following measurement conditions, of preferably about 15 MPa or more, more preferably about 18 MPa or more, even more preferably about 20 MPa or more, and still more preferably about 25 MPa or more. The upper limit is preferably lower than the tensile strength of an exterior material for an electricity storage device, for example, about 500 MPa or less, about 200 MPa or less, about 100 MPa or less, about 50 MPa, or about 35 MPa or less, and a preferred range is about 15 to 500 MPa. Examples of the pressure include about 15 to 200 MPa, about 15 to 100 MPa, about 15 to 50 MPa, about 15 to 35 MPa, about 18 to 500 MPa, about 18 to 200 MPa, about 18 to 100 MPa, about 18 to 50 MPa, about 18 to 35 MPa, about 20 to 500 MPa, about 20 to 200 MPa, about 20 to 100 MPa, about 20 to 50 MPa, about 20 to 35 MPa, about 25 to 500 MPa, about 25 to 200 MPa, about 25 to 100 MPa, about 25 to 50 MPa, and about 25 to 35 MPa.

[0049] (Measurement conditions) Using a tensile tester, the tensile strength is determined at a stroke of 1 mm. Test piece shape: No. 7 dumbbell Test piece width: 2 mm Test piece thickness: measured with a thickness gauge Gauge distance: 10 mm Tensile speed: 50 mm / min Test environment: 23±5°C, 50±30% RH Number of measurements: average of 3

[0050] The adhesive film 1 of the present disclosure has a configuration in which at least a base layer and an adhesive layer are laminated together, and it is preferable that the adhesive layer constitutes one surface of the adhesive film 1 .

[0051] At least one of the substrate layers included in the adhesive film of the present disclosure (first substrate layer) contains a fluororesin. Fluororesins have high carbon dioxide permeability and low water vapor permeability, and therefore, when adhered to the exterior material of an electricity storage device, the adhesive film of the present disclosure can suppress the penetration of water vapor from the outside and efficiently discharge gas generated inside the electricity storage device. Furthermore, for example, polyolefin-based resins are resins with low water vapor permeability and high carbon dioxide permeability, and are suitable as resins included in the adhesive film 1 of the present disclosure.

[0052] The type of fluororesin is not particularly limited as long as it does not impair the effects of the present disclosure, and preferably includes at least one selected from the group consisting of polytetrafluoroethylene (PTFE), perfluoroalkoxyalkane (PFA), perfluoroethylenepropene copolymer (FEP), ethylenetetrafluoroethylene copolymer (ETFE), polyvinylidene fluoride (PVDF), polychlorotrifluoroethylene (PCTFE), and ethylenechlorotrifluoroethylene copolymer (ECTFE), and more preferably includes polytetrafluoroethylene (PTFE).

[0053] In the adhesive film of the present disclosure, the adhesive layer preferably contains a polyolefin resin.

[0054] On the other hand, polyester, polyamide, polyurethane, polycarbonate, polyvinyl alcohol, etc. have high water vapor permeability and are therefore unsuitable as resins for constituting the adhesive film 1 of the present disclosure. Furthermore, polyester, polyamide, vinyl fluoride resin, AS resin (acrylonitrile-styrene copolymer), polyacetal, etc. have low carbon dioxide gas permeability and are therefore unsuitable as resins for constituting the adhesive film 1 of the present disclosure.

[0055] The adhesive film 1 may include two or more base layers and two or more adhesive layers. That is, the adhesive film of the present disclosure includes at least one base layer and at least one adhesive layer. For example, Fig. 21 illustrates a layered structure including base layer 11 and base layer 13, and Fig. 22 illustrates a layered structure including base layer 11, base layer 13, adhesive layer 12, and adhesive layer 14.

[0056] The laminate structure of the adhesive film 1 of the present disclosure may be a two-layer structure, a three-layer structure, a four-layer structure, a five-layer structure, or the like. Among these, a three-layer structure or a four-layer structure is preferred, and a four-layer structure is even more preferred. Specific examples of the laminate structure of the adhesive film 1 of the present disclosure include a two-layer structure in which a base layer 11 and an adhesive layer 12 are laminated in this order (see FIG. 20 ); a three-layer structure in which an adhesive layer 12, a base layer 11, and a base layer 13 are laminated in this order (see FIG. 21 ); and a four-layer structure in which an adhesive layer 12, a base layer 11, an adhesive layer 14, and a base layer 13 are laminated in this order (see FIG. 22 ).

[0057] From the viewpoint of optimally exhibiting the effects of the present disclosure, the total thickness of the adhesive film 1 of the present disclosure is, for example, about 5 μm or more, preferably about 20 μm or more, and more preferably about 30 μm or more. The total thickness of the adhesive film 1 of the present disclosure is, for example, about 500 μm or less, preferably about 200 μm or less, and more preferably 180 μm or less. Preferred ranges for the total thickness of the adhesive film 1 of the present disclosure include about 5 to 500 μm, about 5 to 200 μm, about 5 to 180 μm, about 20 to 500 μm, about 20 to 200 μm, about 20 to 180 μm, about 30 to 500 μm, about 30 to 200 μm, and about 30 to 180 μm. As a more specific example, when the adhesive film 1 of the present disclosure is used in a consumer electricity storage device, the total thickness is preferably about 60 to 300 μm, and when it is used in an in-vehicle electricity storage device, the total thickness is preferably about 80 to 500 μm.

[0058] The materials constituting the substrate layer and adhesive layer, thickness, etc., included in the adhesive film 1 of the present disclosure will be described in detail below.

[0059] [Substrate Layer] In the adhesive film of the present disclosure, the substrate layer is a layer that functions as a support.

[0060] The substrate layer is preferably formed from a resin with low water vapor permeability and high carbon dioxide permeability. At least one of the substrate layers included in the adhesive film of the present disclosure contains a fluororesin. The substrate layer (first substrate layer) containing a fluororesin may contain only one type of resin, or two or more types of resins. The substrate layer containing a fluororesin preferably contains a fluororesin as a main component, and is preferably formed from a fluororesin film. The fluororesin film is a resin film containing a fluororesin as a main component. Incidentally, the substrate layer containing a fluororesin as a main component means that the proportion of the fluororesin in the resin constituting the substrate layer is 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 98% by mass or more, and may even be 100% by mass. In particular, at least one of the substrate layers included in the adhesive film of the present disclosure preferably contains PTFE. The resin contained in the PTFE-containing substrate layer (first substrate layer) may be only one type, or may be two or more types. The PTFE-containing substrate layer preferably contains PTFE as a main component, and is preferably formed of a PTFE film. The PTFE film is a resin film containing PTFE as a main component. Note that, "the substrate layer contains PTFE as a main component" means that the proportion of PTFE in the resin constituting the substrate layer is 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 98% by mass or more, and may even be 100% by mass.

[0061] The surface of the base layer may be subjected to a surface treatment in order to improve the adhesion between the base layer and the adhesive layer, etc. The surface treatment is not particularly limited as long as it improves the adhesion, and examples thereof include chemical etching treatment, plasma treatment, corona treatment, primer treatment, blast treatment, and sputter etching treatment.

[0062] The thickness of the substrate layer containing a fluororesin is preferably about 12 μm or more, more preferably about 25 μm or more, and even more preferably about 38 μm or more, and is preferably about 150 μm or less, more preferably about 100 μm or less, and even more preferably about 75 μm or less, with preferred ranges including about 12 to 150 μm, about 12 to 100 μm, about 12 to 75 μm, about 25 to 150 μm, about 25 to 100 μm, about 25 to 75 μm, about 38 to 150 μm, about 38 to 100 μm, and about 38 to 75 μm. A thickness of 12 μm or more is preferred to make the substrate layer suitable as a support, and a thickness of 150 μm or less is preferred to make the carbon dioxide permeability of the substrate layer suitable.

[0063] Furthermore, from the viewpoint of enhancing the mechanical strength of the adhesive film while favorably exhibiting the effects of the present disclosure, the substrate layer of the adhesive film of the present disclosure preferably contains a nonwoven fabric. More specifically, it is preferable that the adhesive film further includes a substrate layer (second substrate layer) made of nonwoven fabric in addition to a substrate layer (first substrate layer) containing PTFE.

[0064] The resin constituting the nonwoven fabric is not particularly limited, and examples thereof include polyarylate, aramid, polyethylene, polyvinyl alcohol (PVA), polyparaphenylene benzobisoxazole (PBO), polyphenylene sulfide (PPS), polyimide, etc. The resin constituting the nonwoven fabric may be one type or two or more types. Note that nonwoven fabrics have high carbon dioxide permeability but also high water vapor permeability, and therefore are used in the adhesive film of the present disclosure primarily for the purpose of increasing mechanical strength.

[0065] The basis weight of the base material layer made of nonwoven fabric is preferably about 10 g / m 2 More preferably, about 15 g / m 2 More preferably, about 20 g / m 2 or more, and preferably about 100 g / m 2 or less, more preferably about 75 g / m 2 More preferably, about 50 g / m or less 2The preferred range is 10 to 100 g / m 2 degree, 10-75g / m 2 degree, 10-50g / m 2 degree, 15-100g / m 2 degree, 15-75g / m 2 degree, 15-50g / m 2 degree, 20-100g / m 2 degree, 20-75g / m 2 degree, 20-50g / m 2 The degree of

[0066] The adhesive film of the present disclosure may further include a substrate layer (third substrate layer) formed of another resin film in addition to the substrate layer (first substrate layer) containing PTFE. As described above, the substrate layer is preferably formed of a resin having a low water vapor permeability and a high carbon dioxide permeability, and it is preferable to select such a resin (for example, a polyolefin resin) as the resin forming the other resin film.

[0067] The adhesive film of the present disclosure preferably includes, as substrate layers, a substrate layer (first substrate layer) containing PTFE and a substrate layer (second substrate layer) made of nonwoven fabric, and more preferably the substrate layer consists of only these two layers, which are bonded together via an adhesive layer (second adhesive layer) described below.

[0068] In the present disclosure, from the viewpoint of more suitably exerting the effects of the present disclosure, the ratio of the thickness of the base layer to the total thickness (100%) of the adhesive film 1 (when there are two or more base layers, the total ratio of the thickness) is preferably about 5% or more, more preferably about 10% or more, even more preferably about 15% or more, and is also preferably about 95% or less, more preferably about 90% or less, even more preferably about 85% or less, and preferred ranges are about 5 to 95%, about 5 to 90%, about 5 to 85%, about 10 to 95%, about 10 to 90%, about 10 to 85%, about 15 to 95%, about 15 to 90%, and about 15 to 85%.

[0069] [Adhesive Layer] The adhesive layer (first adhesive layer) constituting at least one surface of the adhesive film of the present disclosure is a layer that has adhesiveness to the exterior material of the electricity storage device. In the specific example described above, it has adhesiveness to the surface or welded portion of the exterior material 3 (preferably heat-sealing property to the welded portion).

[0070] 1 to 4, when the adhesive film 1 is applied to an exterior packaging material 3 made of a metal can, the adhesive layer of the adhesive film 1 can be made of a resin that is water-impermeable and gas-permeable and has adhesive properties (preferably heat-sealing properties) to the metal that constitutes the outer surface of the exterior packaging material 3. Also, when the adhesive film 1 is applied to the outer surface of the exterior packaging material 3 made of the laminated film, as shown in FIGS. 5 to 9, the adhesive layer of the adhesive film 1 can be made of a resin that is water-impermeable and gas-permeable and has adhesive properties (preferably heat-sealing properties) to the resin that constitutes the outer surface of the exterior packaging material.

[0071] Furthermore, as described above, when the adhesive film 1 is applied to an exterior packaging material 3 made of a laminated film (a laminate having at least a base material layer 31, a barrier layer 33, and a heat-sealable resin layer 35 in this order), as shown in Figures 10 to 12 and 14 to 19, the adhesive film 1 can be made of a resin that is water-impermeable and gas-permeable and has adhesiveness (preferably heat-sealability) to the resin that makes up the innermost layer of the exterior packaging material (i.e., the heat-sealable resin layer 35 of the exterior packaging material 3 described below).

[0072] Furthermore, as described above, when the adhesive film of the present disclosure has two or more base layers, it may further have an adhesive layer (second adhesive layer) that bonds these base layers together.

[0073] The adhesive layer contained in the adhesive film of the present disclosure is preferably formed from a resin that has a low water vapor permeability and a high carbon dioxide permeability.

[0074] The adhesive layer is preferably a layer containing a polyolefin resin (i.e., having a polyolefin skeleton), and more preferably a layer formed of a polyolefin resin. Examples of polyolefin resins include polyolefins such as polyethylene and polypropylene. The polyolefin resin may also be an acid-modified polyolefin (acid-modified polyolefin). The acid-modified polyolefin is not particularly limited as long as it is an acid-modified polyolefin, but preferably includes polyolefins graft-modified with an unsaturated carboxylic acid or its anhydride, such as acid-modified polyethylene and acid-modified polypropylene. Acid-modified polyolefins such as acid-modified polypropylene have high adhesion to metals or resins and, further, have particularly high carbon dioxide permeability, making them particularly suitable as resins for forming adhesive layers.

[0075] Examples of polyolefins include polyethylenes such as low-density polyethylene, medium-density polyethylene, high-density polyethylene, and linear low-density polyethylene; crystalline or amorphous polypropylenes such as homopolypropylene, 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. Of these polyolefins, polyethylene and polypropylene are preferred.

[0076] The polyolefin may also be a cyclic polyolefin. Cyclic polyolefins are copolymers of olefins and cyclic monomers, and examples of olefins constituting the cyclic polyolefin include ethylene, propylene, 4-methyl-1-pentene, butadiene, and isoprene. Examples of 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, cyclic alkenes are preferred, and norbornene is more preferred. Styrene is also an example of a constituting monomer.

[0077] In the acid-modified polyolefin, the polyolefin to be acid-modified is preferably the polyolefin described above. For example, the carboxylic acid-modified cyclic polyolefin is a polymer obtained by copolymerizing a cyclic polyolefin by substituting an α,β-unsaturated carboxylic acid or an anhydride thereof for a portion of the monomers constituting the cyclic polyolefin, or by block polymerizing or graft polymerizing an α,β-unsaturated carboxylic acid or an anhydride thereof with a cyclic polyolefin.

[0078] Examples of carboxylic acids or anhydrides thereof used for acid modification include maleic acid, acrylic acid, itaconic acid, crotonic acid, maleic anhydride, itaconic anhydride, etc. When a polyolefin resin is analyzed by infrared spectroscopy, a peak derived from maleic anhydride is preferably detected. For example, when a 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 1780 cm -1 A peak derived from maleic anhydride is detected around 1000 Hz. In other words, in this case, when the polyolefin resin is measured by infrared spectroscopy, a peak derived from maleic anhydride is detected. 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.

[0079] The adhesive layer may be formed from one resin component alone, or may be formed from a blend polymer combining two or more resin components. From the viewpoint of film-forming properties of the adhesive layer, it is preferable to form it from a blend polymer combining two or more resin components. When using a blend polymer, it is preferable that the adhesive layer contains acid-modified polypropylene as the main component (50% by mass or more of a component) and 50% by mass or less of another resin (preferably polyethylene from the viewpoint of improving flexibility). On the other hand, from the viewpoint of improving the electrolyte resistance of the adhesive layer, it is preferable that the adhesive layer contains polypropylene or acid-modified polypropylene alone as the resin.

[0080] The adhesive layer may also contain a pressure-sensitive adhesive component, such as an elastomer.

[0081] The elastomer is not particularly limited as long as it exhibits adhesiveness when blended with polyolefin, and for example, an elastomer made of a thermoplastic resin (thermoplastic elastomer) is preferred.

[0082] Preferred examples of the elastomer include styrene-based elastomers, olefin-based elastomers, acrylic-based elastomers, silicone-based elastomers, urethane-based elastomers, polyester-based elastomers, polyamide-based elastomers, rubber-based elastomers, etc. The elastomers may be used alone or in combination of two or more.

[0083] The type of styrene-based elastomer is not particularly limited, but specific examples include styrene-butadiene-styrene block copolymer, styrene-isoprene-styrene block copolymer, styrene-ethylene-butylene-styrene block copolymer, and styrene-ethylene-propylene-styrene block copolymer.

[0084] Examples of olefin elastomers include copolymers of α-olefins having 2 to 20 carbon atoms, such as ethylene, propylene, 1-butene, 1-hexene, and 4-methylpentene. Suitable examples include ethylene-propylene copolymer (EPR) and ethylene-propylene-diene copolymer (EPDM). Other examples include copolymers of α-olefins with non-conjugated dienes having 2 to 20 carbon atoms, such as dicyclopentadiene, 1,4-hexadiene, cyclooctadiene, methylenenorbornene, ethylidenenorbornene, butadiene, and isoprene. Further examples include carboxy-modified nitrile rubber obtained by copolymerizing methacrylic acid with a butadiene-acrylonitrile copolymer.

[0085] Acrylic elastomers are primarily composed of acrylic esters, and specifically, ethyl acrylate, butyl acrylate, methoxyethyl acrylate, ethoxyethyl acrylate, etc. are preferably used. Furthermore, glycidyl methacrylate, allyl glycidyl ether, etc. are used as crosslinking point monomers. Furthermore, acrylonitrile and ethylene can also be copolymerized. Specific examples include acrylonitrile-butyl acrylate copolymer, acrylonitrile-butyl acrylate-ethyl acrylate copolymer, and acrylonitrile-butyl acrylate-glycidyl methacrylate copolymer.

[0086] Silicone elastomers are those containing organopolysiloxane as a main component, and examples thereof include polydimethylsiloxane-based, polymethylphenylsiloxane-based, and polydiphenylsiloxane-based elastomers.

[0087] Urethane elastomers are composed of structural units of a hard segment made of low-molecular-weight ethylene glycol and diisocyanate, and a soft segment made of a high-molecular-weight (long-chain) diol and diisocyanate. Examples of high-molecular-weight (long-chain) diols include polypropylene glycol, polytetramethylene oxide, poly(1,4-butylene adipate), poly(ethylene-1,4-butylene adipate), polycaprolactone, poly(1,6-hexylene carbonate), and poly(1,6-hexylene neopentylene adipate).

[0088] Polyester elastomers are obtained by polycondensation of dicarboxylic acids or their derivatives with diol compounds or their derivatives. Specific examples of dicarboxylic acids include aromatic dicarboxylic acids such as terephthalic acid, isophthalic acid, and naphthalenedicarboxylic acid, and aromatic dicarboxylic acids in which the hydrogen atoms of the aromatic nuclei are substituted with methyl groups, ethyl groups, phenyl groups, etc.; aliphatic dicarboxylic acids having 2 to 20 carbon atoms such as adipic acid, sebacic acid, and dodecanedicarboxylic acid; and alicyclic dicarboxylic acids such as cyclohexanedicarboxylic acid. These compounds can be used alone or in combination of two or more.

[0089] Specific examples of the diol compound include aliphatic diols and alicyclic diols such as ethylene glycol, 1,3-propanediol, 1,4-butanediol, 1,6-hexanediol, 1,10-decanediol, and 1,4-cyclohexanediol, as well as bisphenol A, bis-(4-hydroxyphenyl)-methane, bis-(4-hydroxy-3-methylphenyl)-propane, and resorcinol. These compounds can be used alone or in combination of two or more.

[0090] Examples of polyamide-based elastomers include block copolymers in which polyamide is used as a hard segment component and polybutadiene, butadiene-acrylonitrile copolymer, styrene-butadiene copolymer, polyisoprene, ethylene-propylene copolymer, polyether, polyester, polybutadiene, polycarbonate, polyacrylate, polymethacrylate, polyurethane, silicone rubber, or the like is used as a soft segment component.

[0091] An example of the rubber elastomer is polyisobutylene.

[0092] Among the elastomers, styrene-based elastomers and olefin-based elastomers are preferred, with styrene-based elastomers being particularly preferred.

[0093] The proportion of the elastomer contained in the adhesive layer is not particularly limited, but is preferably about 50% by mass or less, more preferably about 10 to 50% by mass, and even more preferably about 10 to 40% by mass.

[0094] Since the adhesive layer has excellent thermal fusion properties, the melting peak temperature of the resin constituting the adhesive layer is preferably 300 ° C. or less, more preferably 200 ° C. or less, and even more preferably 160 ° C. or less, and is preferably 100 ° C. or more, more preferably 120 ° C. or more, and even more preferably 140 ° C. or more. Preferred ranges are about 100 to 300 ° C., about 100 to 200 ° C., about 100 to 160 ° C., about 120 to 300 ° C., about 120 to 200 ° C., about 120 to 160 ° C., about 140 to 300 ° C., about 140 to 200 ° C., and about 140 to 160 ° C.

[0095] Furthermore, from the viewpoint of more suitably achieving the effects of the present disclosure, the thickness of the adhesive layer is preferably about 10 μm or more, more preferably about 20 μm or more, and even more preferably about 30 μm or more, and is preferably about 300 μm or less, more preferably about 200 μm or less, and even more preferably about 150 μm or less, and preferred ranges are about 10 to 300 μm, about 10 to 200 μm, about 10 to 150 μm, about 20 to 300 μm, about 20 to 200 μm, about 20 to 150 μm, about 30 to 300 μm, about 30 to 200 μm, and about 30 to 150 μm.

[0096] In the present disclosure, from the viewpoint of more suitably exerting the effects of the present disclosure, the ratio of the thickness of the adhesive layer (total ratio of thickness when there are two or more adhesive layers) to the total thickness (100%) of the adhesive film 1 is preferably about 5% or more, more preferably about 10% or more, even more preferably about 15% or more, and is also preferably about 95% or less, more preferably about 90% or less, even more preferably about 85% or less, with preferred ranges being about 5 to 95%, about 5 to 90%, about 5 to 85%, about 10 to 95%, about 10 to 90%, about 10 to 85%, about 15 to 95%, about 15 to 90%, and about 15 to 85%.

[0097] From the viewpoint of more suitably exhibiting the effects of the present disclosure, it is also preferable that the adhesive film 1 is substantially free of polyester, polyamide, polyurethane, polycarbonate, polyvinyl alcohol, vinyl fluoride resin, AS resin, or polyacetal. "Substantially free of these resins" means that the total proportion of these resins in the adhesive film 1 is 5% by mass or less, further 1% by mass or less, or even 0% by mass. From the viewpoint of more suitably exhibiting the effects of the present disclosure, the total proportion of fluororesin and polyolefin resin in the resins constituting the adhesive film 1 is preferably 90% by mass or more, more preferably 95% by mass or more, even more preferably 98% by mass or more, and even more preferably 100% by mass.

[0098] At least one of the layers constituting the adhesive film 1 of the present disclosure may contain, in addition to a resin, additives such as a colorant such as a pigment, a filler, and a lubricant.

[0099] The adhesive film 1 of the present disclosure has high carbon dioxide permeability, low water vapor permeability, and high mechanical strength, and is therefore particularly preferably provided with the following laminate structure 1 or 2. Lamination structure 1: A laminate structure in which an adhesive layer formed from acid-modified polypropylene / a base layer formed from a fluororesin film / an adhesive layer formed from acid-modified polypropylene / a base layer formed from a polyarylate nonwoven fabric are laminated in this order. Lamination structure 2: A laminate structure in which an adhesive layer formed from acid-modified polypropylene / a base layer formed from a polyarylate nonwoven fabric / an adhesive layer formed from acid-modified polypropylene / a base layer formed from a fluororesin film are laminated in this order.

[0100] Furthermore, among the laminated structures 1 and 2, laminated structure 1, in which a substrate layer formed of a fluororesin film is laminated adjacent to the adhesive layer constituting one surface of adhesive film 1, is particularly preferred from the viewpoint of airtightness of the packaging material. This is because the substrate layer formed of a fluororesin film with extremely low water vapor permeability is located closer to the communicating holes through which water vapor passes.

[0101] [Sheathing material 3] Examples of the sheathing material 3 of the electricity storage device 10 include a metal can and a laminated film. For example, Figures 1 and 2 illustrate an embodiment in which the sheathing material 3 of the electricity storage device 10 is configured as a rectangular metal can. Figures 3 and 4 illustrate an embodiment in which the sheathing material 3 of the electricity storage device 10 is configured as a cylindrical metal can. Figures 5 to 12 and 14 to 19 illustrate an embodiment in which the sheathing material 3 of the electricity storage device 10 is configured as a laminated film (for example, a laminate including at least a base layer 31, a barrier layer 33, and a heat-sealable resin layer 35 in this order).

[0102] In addition to the exterior material 3, at least terminals 2 are provided on the outer surface of the electricity storage device 10. The terminals 2 are members that electrically connect the inside and outside of the electricity storage device 10 and are used to extract electricity from the electricity storage device 10.

[0103] When the exterior material is a metal can, the exterior material is made of a metal, and examples of the metal include stainless steel, aluminum alloy, and steel plate.

[0104] Furthermore, the packaging material 3 made of a laminate film may have a laminate structure consisting of a laminate having at least a base material layer 31, a barrier layer 33, and a heat-sealable resin layer 35 in this order. FIG. 23 shows an example of a cross-sectional structure of the packaging material 3, in which the base material layer 31, an optional adhesive layer 32, a barrier layer 33, an optional adhesive layer 34, and a heat-sealable resin layer 35 are laminated in this order. In the packaging material 3, the base material layer 31 is the outer layer, and the heat-sealable resin layer 35 is the innermost layer. During assembly of the electricity storage device, the heat-sealable resin layers 35 located on the periphery of the electricity storage device elements 4 are brought into contact with each other and heat-sealed to seal the electricity storage device elements 4. Note that although FIGS. 5 to 12 and 14 to 19 illustrate electricity storage devices 10 using embossed packaging materials 3 formed by embossing or the like, the packaging material 3 may be an unformed pouch type. The pouch type includes three-sided seal, four-sided seal, pillow type, etc., and any type may be used.

[0105] The exterior packaging material 3 may also be formed from a laminate including at least a barrier layer 33 and a heat-sealable resin layer 35 in this order. In this laminate, the base material layer 31 is a layer that is provided as needed, and the side of the barrier layer 33 opposite to the heat-sealable resin layer 35 side is the outermost layer, and the heat-sealable resin layer 35 is the innermost layer.

[0106] The thickness of the laminate constituting the exterior material 3 is not particularly limited, but from the viewpoint of cost reduction, improvement of energy density, etc., examples of the thickness include about 300 μm or less, preferably about 250 μm or less, about 210 μm or less, about 190 μm or less, about 180 μm or less, about 155 μm or less, and about 120 μm or less. Furthermore, from the viewpoint of maintaining the function of the exterior material for an electricity storage device, which is to protect the electricity storage device elements, the thickness of the laminate constituting the electricity storage device exterior material 10 is preferably about 35 μm or more, about 45 μm or more, about 60 μm or more, about 155 μm or more, and about 190 μm or more. Furthermore, preferred ranges for the laminate constituting the exterior packaging material 10 for an electricity storage device are, for example, about 35 to 300 μm, about 35 to 250 μm, about 35 to 210 μm, about 35 to 190 μm, about 35 to 180 μm, about 35 to 155 μm, about 35 to 120 μm, about 45 to 300 μm, about 45 to 250 μm, about 45 to 210 μm, about 45 to 190 μm, about 45 to 180 μm, about 45 to 155 μm, about 45 to 120 μm, about 60 to 300 μm, about 60 to 250 μm, and about 60 to 300 μm. Examples of the thickness include about 210 μm, about 60 to 190 μm, about 60 to 180 μm, about 60 to 155 μm, about 60 to 120 μm, about 155 to 300 μm, about 155 to 250 μm, about 155 to 210 μm, about 155 to 190 μm, about 155 to 180 μm, about 190 to 300 μm, about 190 to 250 μm, and about 190 to 210 μm. In particular, when making the power storage device lightweight and thin, about 60 to 155 μm is preferred, and when improving formability, about 155 to 190 μm is preferred.

[0107] The adhesive film 1 of the present disclosure can also be suitably applied to an exterior material for an all-solid-state battery. The thickness of the laminate constituting the exterior material for an all-solid-state battery is not particularly limited, but from the viewpoints of cost reduction, improving energy density, etc., it is preferably about 10,000 μm or less, about 8,000 μm or less, or about 5,000 μm or less. From the viewpoint of maintaining the function of the exterior material for an all-solid-state battery, which is to protect the battery element, it is preferably about 100 μm or less. Examples of preferred ranges include about 100 to 10,000 μm, about 100 to 8,000 μm, about 100 to 5,000 μm, about 150 to 10,000 μm, about 150 to 8,000 μm, about 150 to 5,000 μm, about 200 to 10,000 μm, about 200 to 8,000 μm, and about 200 to 5,000 μm, and about 100 to 5,000 μm is particularly preferred.

[0108] (Substrate Layer 31) In the packaging material 3, the substrate layer 31 is a layer that functions as a substrate of the packaging material, and is a layer that forms the outermost layer side.

[0109] The material for forming the substrate layer 31 is not particularly limited, as long as it has insulating properties. Examples of materials for forming the substrate layer 31 include polyester, polyamide, epoxy, acrylic, fluororesin, polyurethane, silicone resin, phenol, polyetherimide, polyimide, and mixtures or copolymers thereof. Polyesters such as polyethylene terephthalate and polybutylene terephthalate have the advantage of being highly resistant to electrolyte and being less susceptible to whitening due to adhesion of electrolyte, and are therefore preferably used as materials for forming the substrate layer 31. Furthermore, polyamide film has excellent stretchability and can prevent whitening due to resin cracking of the substrate layer 31 during molding, and is therefore preferably used as materials for forming the substrate layer 31.

[0110] The base layer 31 may be formed of a uniaxially or biaxially stretched resin film or 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.

[0111] Among these, nylon and polyester are preferred, and biaxially oriented nylon and biaxially oriented polyester are more preferred as the resin film forming the base layer 31. In addition, all-solid-state batteries are designed to withstand temperatures of 150°C or higher, so they are often sealed at high temperatures of 200°C or higher, and biaxially oriented polyester is the most suitable.

[0112] The base material layer 31 may be formed by laminating resin films made of different materials to improve pinhole resistance and insulation when used as a package for an electricity storage device. Specific examples include a multilayer structure in which a polyester film and a nylon film are laminated together, or a multilayer structure in which a biaxially oriented polyester film and a biaxially oriented nylon film are laminated together. When the base material layer 31 has a multilayer structure, the resin films may be bonded together via an adhesive, or may be directly laminated together without an adhesive. Bonding without an adhesive can be achieved by, for example, a method of bonding in a hot-melt state, such as coextrusion, sand lamination, or thermal lamination. For the above-mentioned high-temperature sealing, it is desirable that at least the outermost layer be made of biaxially oriented polyester.

[0113] The base layer 31 may be made low-friction to improve formability. When making the base layer 31 low-friction, the coefficient of friction of the surface is not particularly limited, but may be, for example, 1.0 or less. To make the base layer 31 low-friction, for example, matte treatment, formation of a thin film layer of a slip agent, or a combination thereof may be used.

[0114] The thickness of the base layer 31 is, for example, about 10 to 50 μm, and preferably about 15 to 30 μm.

[0115] (Adhesive Layer 32) In the packaging material 3, 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.

[0116] The adhesive layer 32 is formed of an adhesive capable of bonding the base material layer 31 and the barrier layer 33. The adhesive used to form the adhesive layer 32 may be a two-component curing adhesive or a one-component curing adhesive. The bonding mechanism of the adhesive used to form the adhesive layer 32 is not particularly limited, and may be any of a chemical reaction type, a solvent volatilization type, a hot melt type, a hot pressure type, or the like.

[0117] The resin component of the adhesive that can be used to form the adhesive layer 32 is preferably a polyurethane-based two-component curing adhesive; polyamide, polyester, or a blend resin of these with modified polyolefin, from the viewpoint of having excellent ductility, durability under high humidity conditions, yellowing prevention, and thermal degradation prevention during heat sealing, and of effectively suppressing a decrease in the laminate strength between the base material layer 31 and the barrier layer 33 and preventing delamination.

[0118] Furthermore, the adhesive layer 32 may be multi-layered with different adhesive components. When the adhesive layer 32 is multi-layered with different adhesive components, it is preferable to select a resin that has excellent adhesion to the base material layer 31 as the adhesive component disposed on the base material layer 31 side, and an adhesive component that has excellent adhesion to the barrier layer 33 as the adhesive component disposed on the barrier layer 33 side, from the viewpoint of improving the laminate strength between the base material layer 31 and the barrier layer 33. When the adhesive layer 32 is multi-layered with different adhesive components, specifically, the adhesive component disposed 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 copolymer polyester, or the like.

[0119] The thickness of the adhesive layer 32 is, for example, about 2 to 50 μm, and preferably about 3 to 25 μm.

[0120] (Barrier Layer 33) In the exterior packaging material, the barrier layer 33 is a layer that not only improves the strength of the exterior packaging material but also has the function of preventing water vapor, oxygen, light, and the like from penetrating into the interior of the electricity storage device. The barrier layer 33 is preferably a metal layer, i.e., a layer formed of a metal. Specific examples of metals constituting the barrier layer 33 include aluminum, stainless steel, and titanium, and aluminum is preferred. The barrier layer 33 can be formed, for example, from a metal foil, a metal vapor deposition film, an inorganic oxide vapor deposition film, a carbon-containing inorganic oxide vapor deposition film, or a film provided with any of these vapor deposition films. It is preferably formed from a metal foil, and more preferably from an aluminum foil. From the viewpoint of preventing the occurrence of wrinkles or pinholes in the barrier layer 33 during the production of the exterior packaging material, the barrier layer is more preferably 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).

[0121] In the barrier layer 33, the layer made of the aforementioned metal material may contain recycled metal material. Examples of recycled metal material include recycled aluminum alloy, stainless steel, titanium steel, and steel plate. These recycled materials can be obtained by known methods. Recycled aluminum alloy material can be obtained, for example, by the manufacturing method described in International Publication No. 2022 / 092231. The barrier layer 3 may be made of recycled material alone, or may be made of a mixture of recycled and virgin material. Note that recycled metal material refers to metal material that has been made reusable by collecting, isolating, and refining various products used in the market or waste from manufacturing processes. Furthermore, virgin metal material refers to new metal material refined from natural metal resources (raw materials) and is not recycled material.

[0122] The thickness of the barrier layer 33 is preferably about 10 to 200 μm, more preferably about 20 to 100 μm, from the viewpoint of making the exterior material thinner and making it difficult for pinholes to occur during molding.

[0123] Furthermore, it is preferable that at least one surface, and preferably both surfaces, of the barrier layer 33 be chemically treated in order to stabilize adhesion, prevent dissolution and corrosion, etc. Here, chemical treatment refers to a treatment for forming a corrosion-resistant film on the surface of the barrier layer.

[0124] (Adhesive Layer 34) In the packaging material 3, the adhesive layer 34 is a layer that is provided as needed between the barrier layer 33 and the heat-sealable resin layer 35 in order to firmly bond the heat-sealable resin layer 35.

[0125] The adhesive layer 34 is formed of an adhesive capable of bonding the barrier layer 33 and the heat-fusible resin layer 35. The composition of the adhesive used to form the adhesive layer is not particularly limited, but examples thereof include an adhesive made of a polyester polyol compound and an alicyclic isocyanate compound.

[0126] The thickness of the adhesive layer 34 is, for example, about 1 to 40 μm, and preferably about 2 to 30 μm.

[0127] (Heat-Fusible Resin Layer 35) In the exterior packaging material 3, the heat-fusible resin layer 35 corresponds to the innermost layer, and is a layer that seals the electricity storage device elements by heat-fusing the heat-fusible resin layers together when assembling the electricity storage device.

[0128] The resin component used in the heat-fusible resin layer 35 is not particularly limited as long as it is heat-fusible, but for example, in the case of exterior materials, polyolefins and cyclic polyolefins are generally used.

[0129] Specific examples of the polyolefin include polyethylenes such as low-density polyethylene, medium-density polyethylene, high-density polyethylene, and linear low-density polyethylene; crystalline or amorphous polypropylenes such as homopolypropylene, block copolymers of polypropylene (e.g., block copolymers of propylene and ethylene), and random copolymers of polypropylene (e.g., random copolymers of propylene and ethylene); and ethylene-butene-propylene terpolymers. Among these polyolefins, polyethylene and polypropylene are preferred.

[0130] The cyclic polyolefin is a copolymer of an olefin and a cyclic monomer, and examples of the olefin constituting the cyclic polyolefin include ethylene, propylene, 4-methyl-1-pentene, butadiene, and isoprene. Examples of the cyclic monomer constituting the cyclic polyolefin include cyclic alkenes such as norbornene; specifically, cyclic dienes such as cyclopentadiene, dicyclopentadiene, cyclohexadiene, and norbornadiene. Among these polyolefins, preferred are cyclic alkenes, and more preferred are norbornene. Another example of the constituting monomer is styrene.

[0131] 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.

[0132] 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. Furthermore, 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.

[0133] The thickness of the heat-fusible resin layer 35 is not particularly limited, but may be about 2 to 2000 μm, preferably about 5 to 1000 μm, and more preferably about 10 to 500 μm.

[0134] As described above, it is more desirable that the melting peak temperature of the heat-sealable resin layer 35 of the packaging material 3 is above 100°C, which is the lower limit of the melting peak temperature of the base material layer. The melting peak temperature of the heat-sealable resin layer 35 is preferably 150 to 250°C, more preferably 180 to 270°C, even more preferably 200 to 270°C, and even more preferably 200 to 250°C. As described above, from the viewpoint of more suitably exhibiting the effects of the present disclosure, the melting peak temperature of the base material layer is preferably a value that is 5°C or more lower than the melting peak temperature of the heat-sealable resin layer 35 of the packaging material 3, more preferably a value that is 10°C or more lower, and even more preferably a value that is 15°C or more lower.

[0135] Examples of resins contained in the heat-sealable resin layer 35 of the all-solid-state battery exterior packaging material include polyolefins such as polypropylene and polyethylene, acid-modified polyolefins such as acid-modified polypropylene and acid-modified polyethylene, and polybutylene terephthalate. Among these, polybutylene terephthalate has excellent heat resistance, so in the all-solid-state battery exterior packaging material, the heat-sealable resin layer 35 is preferably formed from a polybutylene terephthalate film. Furthermore, forming the heat-sealable resin layer 35 from a polybutylene terephthalate film also provides excellent adhesion to the substrate layer of the adhesive film of the present disclosure. The polybutylene terephthalate film forming the heat-sealable resin layer 35 may be formed by laminating a pre-prepared polybutylene terephthalate film with the adhesive layer 34, or the resin forming the polybutylene terephthalate film may be melt-extruded to form a film and then laminated with the adhesive layer 34.

[0136] The polybutylene terephthalate film may be a stretched polybutylene terephthalate film or an unstretched polybutylene terephthalate film, and is preferably an unstretched polybutylene terephthalate film.

[0137] The polybutylene terephthalate film preferably further contains an elastomer in addition to polybutylene terephthalate. The elastomer serves to ensure the durability of the polybutylene terephthalate film in high-temperature environments while increasing its flexibility. Preferred elastomers include at least one thermoplastic elastomer selected from polyesters, polyamides, polyurethanes, polyolefins, polystyrenes, and polyethers, or thermoplastic elastomer copolymers thereof. The content of the elastomer in the polybutylene terephthalate film is not particularly limited as long as it ensures the durability of the polybutylene terephthalate film in high-temperature environments while increasing its flexibility. For example, the content may be about 0.1% by mass or more, preferably about 0.5% by mass or more, more preferably about 1.0% by mass or more, and even more preferably about 3.0% by mass or more. The content may be, for example, about 10.0% by mass or less, about 8.0% by mass or less, or about 5.0% by mass or less. Preferred ranges of the content include about 0.1 to 10.0 mass%, about 0.1 to 8.0 mass%, about 0.1 to 5.0 mass%, about 0.5 to 10.0 mass%, about 0.5 to 8.0 mass%, about 0.5 to 5.0 mass%, about 1.0 to 10.0 mass%, about 1.0 to 8.0 mass%, about 1.0 to 5.0 mass%, about 3.0 to 10.0 mass%, about 3.0 to 8.0 mass%, and about 3.0 to 5.0 mass%.

[0138] The heat-sealable resin layer 35 may be formed of only one layer, or may be formed of two or more layers of the same or different resins. When the heat-sealable resin layer 35 is formed of two or more layers, at least one layer is formed of a polybutylene terephthalate film, and the polybutylene terephthalate film is preferably the innermost layer of the all-solid-state battery packaging material. Furthermore, the layer bonded to the adhesive layer 34 is preferably a polybutylene terephthalate film. When the heat-sealable resin layer 35 is formed of two or more layers, the layer not formed of a polybutylene terephthalate film may be formed of, for example, a polyolefin such as polypropylene or polyethylene, or an acid-modified polyolefin such as acid-modified polypropylene or acid-modified polyethylene. However, since polyolefins and acid-modified polyolefins have lower durability in high-temperature environments than polybutylene terephthalate, the heat-sealable resin layer 35 is preferably formed solely of a polybutylene terephthalate film.

[0139] Electricity Storage Device The electricity storage device 10 of the present disclosure is an electricity storage device having a structure in which an electricity storage device element 4 is housed in a package formed by an exterior material 3 .

[0140] For example, an adhesive film 1 is adhered to the surface of the exterior material 3 of the electricity storage device 10 so as to close a communication part H provided in the exterior material 3, and gas generated inside the electricity storage device 10 is discharged through the communication part H. The cross-sectional diameter of the communication part H (the cross-sectional diameter of the gas flow path) can be set appropriately depending on the size of the electricity storage device 10, etc.

[0141] Furthermore, for example, the adhesive film 1 is disposed so as to be interposed between the welded parts of the exterior material 3 of the electricity storage device 10, and gas generated inside the electricity storage device 10 is discharged through the adhesive film 1 disposed at the welded parts. The cross-sectional diameter of the part interposed between the welded parts (the cross-sectional diameter of the gas flow path) can be set appropriately according to the size of the electricity storage device 10.

[0142] The adhesive film 1 and the packaging material 3 are as described above.

[0143] For example, the exterior packaging material 3 made of a laminate film is composed of a laminate including, from the outside, at least a base material layer 31, a barrier layer 33, and a heat-sealable resin layer 35 in this order, and the heat-sealable resin layers 35 of the exterior packaging material 3 are heat-sealed to each other, thereby housing the electricity storage device element 4 in the package. For example, an adhesive film 1 is disposed between the heat-sealable resin layers 35 at positions where the heat-sealable resin layers 35 are welded (heat-sealed) to each other. The electricity storage device 10 of the present disclosure can be manufactured by a method including a housing step of housing the electricity storage device element 4 in the package by disposing the adhesive film 1 between the heat-sealable resin layers 35 at positions where the heat-sealable resin layers 35 of the exterior packaging material 3 are heat-sealed to each other, and heat-sealing the heat-sealable resin layers 35 to each other via the adhesive film 1. At this time, the adhesive layer of the adhesive film is adhered to the welded portions of the exterior material 3, and the gas is allowed to permeate in the thickness direction of the adhesive film and be discharged. A particularly preferred configuration is one in which the adhesive film 1 is folded back and sandwiched between the welded portions of the exterior material 3 of the electricity storage device 10, as shown in Figures 10 to 12 and 14 to 19.

[0144] An electricity storage device using the packaging material 3 is provided by covering an electricity storage device element including at least a positive electrode, a negative electrode, and an electrolyte with an exterior material 3 in a state in which metal terminals connected to the positive electrode and the negative electrode protrude outward, so that a flange portion (a region where the heat-sealable resin layers contact each other) can be formed around the periphery of the electricity storage device element, and the heat-sealable resin layers of the flange portion are heat-sealed to form a hermetic seal. When the electricity storage device element is housed in a package formed from the packaging material 3, the package is formed so that the heat-sealable resin portion of the packaging material 3 faces inside (the surface that contacts the electricity storage device element). The package may be formed by overlapping two packaging materials 3 with the heat-sealable resin layers facing each other and heat-sealing the peripheral portions of the overlapped packaging materials 3, or by folding one packaging material 3 and overlapping it, and heat-sealing the peripheral portions. When the packaging material 3 is folded over and overlapped, the edges other than the folded edge may be heat-sealed to form a three-sided package, or the packaging material may be folded over and sealed on all four sides so as to form a flange. When the innermost and outermost layers of the packaging material 3 are heat-sealable resin layers, the packaging material may be formed by heat-sealing the innermost heat-sealable resin layer and the outermost heat-sealable resin layer.

[0145] The electricity storage device element may be sealed by a lid in addition to the exterior material 3. That is, the exterior material 3 and the lid constitute an exterior material (an exterior material for an electricity storage device) that hermetically seals the electricity storage device element. For example, the electricity storage device element may be housed inside a cylindrical exterior material 3, and the opening may be closed by the lid. In another example, the electricity storage device element connected to the lid may be housed inside a cylindrical exterior material 3 that has an opening, and the opening may be closed by the lid. The lid and the exterior material 3 are preferably joined by any means. From the viewpoint of reducing dead space between the electricity storage device element and the exterior material 3 to improve the volumetric energy density of the electricity storage device, the exterior material 3 is preferably wrapped around the electricity storage device element and the lid.

[0146] The lid can be formed, for example, from a resin molded product, a metal molded product, an exterior material 3, or a combination thereof. In this disclosure, when the lid is referred to as a resin molded product, this does not include a case where the lid is formed solely from a film as defined by JIS K6900-1994 [Plastics - Terminology]. When the lid is a metal molded product, the lid also functions as a metal terminal, so the metal terminal can be omitted. The lid may be formed from a resin material and a conductive material.

[0147] Furthermore, a recess for accommodating the electricity storage device element may be formed by deep drawing or stretch forming in the exterior packaging material 3. A recess may be provided in one exterior packaging material 3 while not providing a recess in the other exterior packaging material 3, or a recess may also be provided in the other exterior packaging material 3.

[0148] The power storage device 10 of the present disclosure can be a power storage device such as a battery (including a condenser, a capacitor, etc.). The power storage device 10 of the present disclosure may be either a primary battery or a secondary battery, but is preferably a secondary battery. The type of secondary battery is not particularly limited, and examples include lithium ion batteries, lithium ion polymer batteries, all-solid-state batteries, semi-solid batteries, quasi-solid batteries, polymer batteries, all-resin batteries, lead-acid batteries, nickel-metal hydride batteries, nickel-cadmium batteries, nickel-iron batteries, nickel-zinc batteries, silver oxide-zinc batteries, metal-air batteries, polyvalent cation batteries, condensers, and capacitors. Among these secondary batteries, lithium ion batteries and lithium ion polymer batteries are preferred.

[0149] The present disclosure will be described in detail below with reference to examples and comparative examples, but the present disclosure is not limited to the examples.

[0150] <Production of adhesive film> Example 1 Using an extruder and a T-die casting device, a polyarylate nonwoven fabric (basis weight 14 g / m) was used as a substrate layer. 2 On both sides of the sheet, maleic anhydride-modified polypropylene (PPA) was extruded as an adhesive layer, and a PPa (adhesive layer thickness: 44 μm) / nonwoven fabric (basis weight: 14 g / m 2A three-layer semi-finished product (total thickness 100 μm) was obtained in which a polytetrafluoroethylene film (PTFE film, thickness 50 μm) and the above semi-finished product were laminated in this order. Next, a polytetrafluoroethylene film (PTFE film, thickness 50 μm) and the above semi-finished product were prepared, and a silicone sheet / PTFE separator / PTFE (substrate layer thickness 50 μm) / PPA (adhesive layer thickness 44 μm) / non-woven fabric (basis weight 14 g / m) were laminated. 2 The laminate was placed on a press heated to 200°C and left to stand for 16 seconds under a pressure of 0.75 MPa. The heat-sealed laminate was then allowed to cool naturally to 25°C, resulting in a laminate of PTFE (base layer thickness 50 μm) / PPA (adhesive layer thickness 44 μm) / nonwoven fabric (basis weight 14 g / m). 2 ) / PPA (adhesive layer thickness 44 μm) were laminated in this order to obtain a four-layer adhesive film (total thickness 150 μm).

[0151] Example 2 Using an extruder and a T-die casting device, a polyarylate nonwoven fabric (basis weight 14 g / m) was used as a base layer. 2 On one side of the sheet, maleic anhydride-modified polypropylene (PPA) was extruded as an adhesive layer, and a PPa (adhesive layer thickness: 44 μm) / nonwoven fabric (basis weight: 14 g / m 2 ) was laminated in this order to obtain a two-layer semi-finished product 1 (total thickness 56 μm). Next, a polytetrafluoroethylene film (PTFE film, thickness 50 μm) and maleic anhydride-modified polypropylene (PPa) as an adhesive layer were prepared, and the laminated order was silicone sheet / PTFE separator / PTFE (base layer thickness 50 μm) / PPa (adhesive layer thickness 50 μm) / PTFE separator / silicone sponge sheet. The laminate was placed on a press heated to 200 ° C. and left to stand for 16 seconds under a pressure of 0.25 MPa. The heat-sealed laminate was then allowed to cool naturally to 25 ° C. to obtain a two-layer semi-finished product 2 (total thickness 100 μm). Next, semi-finished products 1 and 2 were prepared, and a silicone sheet / PTFE separator / PPA (adhesive layer thickness 50 μm) / PTFE (base layer thickness 50 μm) / PPA (adhesive layer thickness 44 μm) / non-woven fabric (basis weight 14 g / m 2The laminate was placed on a press heated to 200°C and left to stand for 16 seconds under a pressure of 0.75 MPa. The heat-sealed laminate was then allowed to cool naturally to 25°C, resulting in a laminate of PPa (adhesive layer, thickness 50 μm) / PTFE (base layer, thickness 50 μm) / PPA (adhesive layer, thickness 44 μm) / nonwoven fabric (basis weight 14 g / m). 2 ) were laminated in this order to obtain a four-layer adhesive film (total thickness 156 μm).

[0152] Example 3 Using an extruder and a T-die casting device, a polyarylate nonwoven fabric (basis weight 14 g / m) was used as a base layer. 2 On one side of the sheet, maleic anhydride-modified polypropylene (PPA) was extruded as an adhesive layer, and a PPa (adhesive layer thickness: 44 μm) / nonwoven fabric (basis weight: 14 g / m 2 Next, a polytetrafluoroethylene film (PTFE film, thickness 50 μm) and polypropylene (PP) as an adhesive layer were prepared, and the laminated order was silicone sheet / PTFE separator / PTFE (base layer thickness 50 μm) / PP (adhesive layer thickness 50 μm) / PTFE separator / silicone sponge sheet. The laminate was placed on a press heated to 200 ° C. and left to stand for 16 seconds under a pressure of 0.25 MPa. The heat-sealed laminate was then allowed to cool naturally to 25 ° C. to obtain a semi-finished product 2 (total thickness 100 μm) with a two-layer structure, in which PTFE (base layer thickness 50 μm) / PP (adhesive layer thickness 50 μm) were laminated in this order. Next, semi-finished products 1 and 2 were prepared, and a silicone sheet / PTFE separator / PP (adhesive layer thickness 50 μm) / PTFE (base layer thickness 50 μm) / PPa (adhesive layer thickness 44 μm) / non-woven fabric (basis weight 14 g / m 2 The laminate was placed on a press heated to 200°C and left to stand for 16 seconds under a pressure of 0.75 MPa. The heat-sealed laminate was then allowed to cool naturally to 25°C, resulting in a laminate of PP (adhesive layer, thickness 50 μm) / PTFE (base layer, thickness 50 μm) / PPa (adhesive layer, thickness 44 μm) / nonwoven fabric (basis weight 14 g / m). 2) were laminated in this order to obtain a four-layer adhesive film (total thickness 156 μm).

[0153] Example 4 Using an extruder and a T-die casting device, a polyarylate nonwoven fabric (basis weight 14 g / m) was used as a base layer. 2 On one side of the sheet, maleic anhydride-modified polypropylene (PPA) was extruded as an adhesive layer, and a PPa (adhesive layer thickness: 44 μm) / nonwoven fabric (basis weight: 14 g / m 2 ) were laminated in this order to obtain a semi-finished product 1 having a two-layer structure (total thickness 56 μm). Next, a polytetrafluoroethylene film (PTFE film, thickness 50 μm) and polypropylene (PP) and maleic anhydride-modified polypropylene (PPa) as adhesive layers were prepared, and the laminated order was silicone sheet / PTFE separator / PTFE (base layer thickness 50 μm) / PPa (adhesive layer thickness 25 μm) / PP (adhesive layer thickness 25 μm) / PTFE separator / silicone sponge sheet. The laminate was placed on a press heated to 200°C and left to stand for 16 seconds under a pressure of 0.25 MPa. The heat-fused laminate was then allowed to cool naturally to 25°C, thereby obtaining a three-layer semi-finished product 2 (total thickness 100 μm) in which PTFE (base layer thickness 50 μm) / PPa (adhesive layer thickness 25 μm) / PP (adhesive layer thickness 25 μm) were laminated in this order. Next, semi-finished products 1 and 2 were prepared, and a silicone sheet / PTFE separator / PP (adhesive layer thickness 25 μm) / PPA (adhesive layer thickness 25 μm) / PTFE (base layer thickness 50 μm) / PPA (adhesive layer thickness 44 μm) / non-woven fabric (basis weight 14 g / m 2 The laminate was placed on a press heated to 200°C and left to stand for 16 seconds under a pressure of 0.75 MPa. The heat-sealed laminate was then allowed to cool naturally to 25°C, resulting in a laminate of PP (adhesive layer, thickness 25 μm) / PPA (adhesive layer, thickness 25 μm) / PTFE (base layer, thickness 50 μm) / PPA (adhesive layer, thickness 44 μm) / nonwoven fabric (basis weight 14 g / m). 2 ) were laminated in this order to obtain a five-layer adhesive film (total thickness 156 μm).

[0154] Comparative Example 1 A polytetrafluoroethylene film (PTFE, thickness 50 μm) was used as an adhesive film having a one-layer structure.

[0155] Comparative Example 2: As a substrate layer, a polyarylate nonwoven fabric (basis weight 14 g / m 2 ) was prepared. Maleic anhydride-modified polypropylene (PPA) was prepared as a resin for forming the adhesive layer. A nonwoven fabric (base layer: basis weight 14 g / m) was prepared using an extruder and a T-die casting machine. 2 ) / PPA (adhesive layer thickness 44 μm) laminated together to obtain a two-layer adhesive film (total thickness 56 μm).

[0156] Comparative Example 3: A polyethylene naphthalate film (PEN, thickness 12 μm) was prepared as the substrate layer. Maleic anhydride-modified polypropylene (PPa) was prepared as the resin for forming the adhesive layer. Using an extruder and a T-die casting machine, a two-layer adhesive film (total thickness 56 μm) was obtained in which PEN (substrate layer, thickness 12 μm) and PPa (adhesive layer, thickness 44 μm) were laminated.

[0157] The adhesive films obtained in the Examples and Comparative Examples were measured for tensile strength, carbon dioxide permeability, and water vapor permeability by the following methods. The results are shown in Table 1.

[0158] <Tensile strength> The tensile strength (MPa) of the adhesive film in the MD direction was measured in accordance with the provisions of JIS K6251:2017 under the following measurement conditions. (Measurement conditions) Using a tensile tester (Shimadzu Autograph AG-X Plus), the tensile strength was determined at a stroke of 1 mm. Test piece shape: Dumbbell No. 7 Test piece width: 2 mm Test piece thickness: measured with a thickness gauge Gauge distance: 10 mm Tensile speed: 50 mm / min Test environment: 23±5°C, 50±30% RH Number of measurements: average of 3

[0159] <Carbon dioxide permeability> The carbon dioxide permeability (cc / m) of the adhesive film was measured under the following measurement conditions in accordance with the provisions of Appendix 2 of JIS K7126-1:2006. 2·day·atm) were measured. (Measurement conditions) Sheet shape: 80 mm diameter circle Differential pressure gas: measured using a water vapor transmission rate measuring device (GTR-3000XATA (GTR TEC)) Test conditions: 60°C, 0% RH Transmission direction: transmission from the base layer side constituting one surface of the adhesive film (transmission from one surface for Comparative Example 1) Number of measurements: 1

[0160] <Water vapor permeability> The water vapor permeability (g / m) of the adhesive film was measured under the following measurement conditions in accordance with the gas chromatography method specified in JIS K7129-4:2019. 2 · day) was measured. (Measurement conditions) Sheet shape: 80 mm diameter circle Differential pressure gas: measured using a water vapor transmission rate measuring device (GTR-3000XATA (GTR TEC)) Test conditions: 60°C, 90% RH Transmission direction: transmission from the adhesive layer side constituting one surface of the adhesive film (transmission from one surface for Comparative Example 1) Number of measurements: 1

[0161]

[0162] In Table 1, PTFE represents polytetrafluoroethylene, PPa represents maleic anhydride-modified polypropylene, PEN represents polyethylene naphthalate, and nonwoven fabric represents polyarylate nonwoven fabric.

[0163] The films of Examples 1 to 4 have a base layer and an adhesive layer, and the base layer contains PTFE. They have very low water vapor permeability and high carbon dioxide permeability, and therefore can be suitably used as adhesive films of the present invention. Furthermore, the adhesive films of Examples 1 to 4 also have high tensile strength values ​​and are excellent in mechanical strength.

[0164] As described above, the present disclosure provides the following aspects of the invention. Item 1. An adhesive film that is adhered to an exterior material of an electricity storage device and used to discharge gas generated inside the electricity storage device, the adhesive film being composed of a laminate including at least a base material layer and an adhesive layer, and the base material layer containing a fluororesin. Item 2. The adhesive film is adhered to a surface of the exterior material of the electricity storage device (a surface on at least one side of the exterior material, for example, the surface on the base material layer side and / or the surface on the heat-sealable resin layer side of the exterior material) so as to block a communication part provided in the exterior material, and is used to discharge gas generated inside the electricity storage device from the communication part, the adhesive layer of the adhesive film being adhered to the surface of the exterior material of the electricity storage device. Item 3. The adhesive film according to Item 2, wherein the surface of the exterior material is made of metal or resin. Item 4. Item 5. The adhesive film according to Item 2 or 3, wherein the communication portion is provided on a bottom surface, a side surface, or a welded portion of the electricity storage device. Item 6. The adhesive film according to Item 5, wherein the adhesive film is arranged so as to be interposed between the welded portions of the exterior material of the electricity storage device, and is used to discharge gas generated inside the electricity storage device, the adhesive layer of the adhesive film being adhered to the welded portions of the exterior material, and the gas permeates in the thickness direction of the adhesive film to be discharged. Item 7. The adhesive film according to Item 5, wherein the adhesive film is folded back between the welded portions of the exterior material of the electricity storage device, and is sandwiched between the welded portions of the exterior material. Item 7. The adhesive film according to item 5 or 6, wherein the packaging material is composed of a laminate having at least a base material layer, a barrier layer, and a heat-sealable resin layer laminated in this order, and the adhesive film is disposed so that the heat-sealable resin layer and the adhesive layer of the adhesive film are adhered to each other at the welded portion of the adhesive film, and the adhesive film is interposed between the welded portion. Item 8. The adhesive film according to item 5 or 6, wherein the welded portion of the packaging material has a communication portion through which a surface of the adhesive film is exposed, and the gas is discharged through the communication portion.Item 9. The adhesive film according to any one of Items 2 to 4 and 8, wherein the communicating portion is circular or rectangular. Item 10. The adhesive film according to any one of Items 1 to 9, wherein the adhesive film comprises two or more base layers. Item 11. The adhesive film according to any one of Items 1 to 10, wherein the adhesive film comprises two or more adhesive layers. Item 12. The adhesive film has a carbon dioxide permeability of 5000 cc / m, measured in accordance with the provisions of Annex 2 of JIS K7126-1:2006 under the following measurement conditions: 2 Item 13. The adhesive film according to any one of items 1 to 11, wherein the water vapor permeability is 25 g / m or more, measured according to the gas chromatography method specified in JIS K7129-4:2019 under the following measurement conditions: - day - atm or more. (Measurement conditions) Sheet shape: 80 mm diameter circle Differential pressure gas: Measured using a water vapor permeability measuring device Test conditions: 60 ° C, 0% RH Permeation direction: Permeation from the substrate layer side constituting one surface of the adhesive film. 2Item 14. The adhesive film according to any one of items 1 to 13, wherein the tensile strength in the machine direction of the adhesive film is 15 MPa or more, as measured in accordance with the provisions of JIS K6251:2017 under the following measurement conditions: (Measurement conditions) The adhesive film according to any one of items 1 to 13, wherein the tensile strength is measured at a stroke of 1 mm using a tensile tester. Test piece shape: No. 7 dumbbell Test piece width: 2 mm Test piece thickness: measured with a thickness gauge Gauge length: 10 mm Pulling speed: 50 mm / min Test environment: 23±5°C, 50±30% RH Item 15. The fluororesin is polytetrafluoroethylene (PTFE), perfluoroalkoxyalkane (PFA), perfluoroethylene propene copolymer (FEP), ethylene tetrafluoroethylene copolymer (ETFE), polyvinylidene fluoride (PVDF), polychlorotrifluoroethylene (PCTFE), and ethylene chlorotrifluoroethylene copolymer (ECTFE). The adhesive film according to any one of items 1 to 14, comprising at least one selected from the group consisting of.

[0165] REFERENCE SIGNS LIST 1 adhesive film 2 terminal 3 packaging material 3a peripheral portion of packaging material 4 electricity storage device element 10 electricity storage device 11 base material layer 12 adhesive layer 13 base material layer 14 adhesive layer 31 base material layer 32 adhesive agent layer 33 barrier layer 34 adhesive layer 35 heat-sealable resin layer H communicating portion HS heat-sealed portion

Claims

1. An adhesive film that is adhered to an exterior material of an electricity storage device and is used to exhaust gas generated inside the electricity storage device, The adhesive film is composed of a laminate including at least a base layer and an adhesive layer, The substrate layer is an adhesive film comprising a fluororesin.

2. the adhesive film is adhered to a surface of the exterior material of the electricity storage device so as to close a communication portion provided in the exterior material of the electricity storage device, and is used to exhaust gas generated inside the electricity storage device through the communication portion; The adhesive film according to claim 1 , wherein the adhesive layer of the adhesive film is adhered to a surface of the exterior material of the electricity storage device.

3. The adhesive film according to claim 2 , wherein the surface of the exterior material is made of a metal or a resin.

4. The adhesive film according to claim 2 , wherein the communication portion is provided on a bottom surface, a side surface, or a welded portion of the electricity storage device.

5. the adhesive film is disposed so as to be interposed between the welded portions of the exterior material of the electricity storage device, and is used to exhaust gas generated inside the electricity storage device; The adhesive layer of the adhesive film is adhered to the welding portion of the exterior material, The adhesive film according to claim 1 , wherein the gas permeates in a thickness direction of the adhesive film and is discharged.

6. The adhesive film according to claim 5 , wherein the adhesive film is folded back and sandwiched between the welded portions of the exterior material of the electricity storage device.

7. The packaging material is composed of a laminate including at least a base layer, a barrier layer, and a heat-sealable resin layer laminated in this order, The adhesive film according to claim 5 or 6, wherein the adhesive film is positioned so that the heat-sealable resin layer and the adhesive layer of the adhesive film are adhered to each other in the welded portion of the adhesive film, and the adhesive film is interposed between the welded portions.

8. the welding portion of the exterior material is provided with a communication portion through which a surface of the adhesive film is exposed, The adhesive film according to claim 5 or 6, wherein the gas is discharged through the communicating portion.

9. The adhesive film according to claim 2 , 3 or 8 , wherein the communicating portion has a circular or rectangular shape.

10. The adhesive film according to claim 1 , 2 , 3 , 5 , or 6 , wherein the adhesive film comprises two or more substrate layers.

11. The adhesive film according to claim 10 , wherein the adhesive film comprises two or more adhesive layers.

12. The adhesive film has a carbon dioxide permeability of 5000 cc / m, as measured under the following measurement conditions in accordance with the provisions of Annex 2 of JIS K7126-1:2006. 2 7. The adhesive film according to claim 1, 2, 3, 5 or 6, wherein the viscosity is 100 sq. m / s or more. (Measurement conditions) Sheet shape: 80mm diameter circle Differential pressure gas: measured using a water vapor transmission rate measuring device Test conditions: 60°C, 0% RH Transmission direction: from the base layer side constituting one surface of the adhesive film

13. The adhesive film has a water vapor permeability of 25 g / m2 or less, as measured under the following measurement conditions in accordance with the gas chromatography method specified in JIS K7129-4:2019. 2 7. The adhesive film according to claim 1, 2, 3, 5 or 6, wherein the adhesion time is 0.5 - 1 day or less. (Measurement conditions) Sheet shape: 80mm diameter circle Differential pressure gas: measured using a water vapor transmission rate measuring device Test conditions: 60°C, 90% RH Transmission direction: from the adhesive layer side that constitutes one surface of the adhesive film

14. The adhesive film according to claim 1, 2, 3, 5 or 6, wherein the adhesive film has a tensile strength in the MD direction measured under the following measurement conditions in accordance with the provisions of JIS K6251:2017 of 15 MPa or more. (Measurement conditions) Using a tensile tester, the tensile strength is determined at a stroke of 1 mm. Shape of test piece: Dumbbell No. 7 Test piece width: 2 mm Thickness of test piece: Measured with a thickness gauge Distance between gauge lines: 10mm Tensile speed: 50 mm / min Test environment: 23±5°C, 50±30% RH

15. The adhesive film according to claim 1, 2, 3, 5 or 6, wherein the fluororesin comprises at least one selected from the group consisting of polytetrafluoroethylene, perfluoroalkoxyalkane, perfluoroethylenepropene copolymer, ethylenetetrafluoroethylene copolymer, polyvinylidene fluoride, polychlorotrifluoroethylene, and ethylenechlorotrifluoroethylene copolymer.

16. An adhesive film as described in claim 1, 2, 3, 5 or 6, wherein the adhesive layer contains a polyolefin-based resin.