Adhesive Film for Metal Terminals and Method for Producing the Same, Metal Terminal with Adhesive Film for Metal Terminals, Exterior Material for Power Storage Devices, Kit Comprising Exterior Material for Power Storage Devices and Adhesive Film for Metal Terminals, and Power Storage Device and Method for Producing the Same

Abstract

At least a first polyolefin layer disposed on the surface on the side of the exterior material for the power storage device, a base material, and a second polyolefin layer disposed on the metal terminal side, and is composed of a laminate provided in this order, the tensile elastic modulus of the adhesive film for metal terminals is 700 MPa or less, the base material is the layer located between the first polyolefin layer and the second polyolefin layer, and is the layer having the largest Martens hardness measured in a direction perpendicular to the cross-section in the thickness direction of the layer, and the absolute value of the difference between the Martens hardness measured in a direction perpendicular to the cross-section in the thickness direction of the base material and the Martens hardness measured in a direction perpendicular to the cross-section in the thickness direction of the first polyolefin layer is 10 N / mm 2 or less, an adhesive film for metal terminals.

Description

Technical Field

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

Background Art

[0002] Conventionally, various types of power storage devices have been developed. In all power storage devices, an exterior material for a power storage device is an essential member for sealing power storage device elements such as electrodes and electrolytes. Conventionally, a metal exterior material for a power storage device has been frequently used as the exterior material for a power storage device. However, in recent years, with the improvement in performance of electric vehicles, hybrid electric vehicles, personal computers, cameras, mobile phones, etc., power storage devices are required to have various shapes, and also to be thinned and lightened. However, the conventionally frequently used metal exterior material for a power storage device has drawbacks that it is difficult to follow the diversification of shapes and there is also a limit to weight reduction.

[0003] Therefore, in recent years, as an exterior material for a power storage device that can be easily processed into various shapes and can achieve thinning and weight reduction, a laminated sheet in which a base material layer / adhesive layer / barrier layer / heat-sealable resin layer are sequentially laminated has been proposed. When using such a laminated film-like exterior material for a power storage device, with the heat-sealable resin layers located in the innermost layer of the exterior material for a power storage device facing each other, the peripheral portion of the exterior material for a power storage device is heat-sealed by heat sealing, whereby the power storage device element is sealed by the exterior material for a power storage device.

[0004] Metal terminals protrude from the heat-sealed portion of the exterior material for the power storage device, and the power storage device element sealed by the exterior material for the power storage device is electrically connected to the outside by the metal terminals electrically connected to the electrodes of the power storage device element. That is, among the portions where the exterior material for the power storage device is heat-sealed, the portions where the metal terminals are present are heat-sealed with the metal terminals sandwiched between the heat-fusible resin layers. Since the metal terminals and the heat-fusible resin layers are made of different materials from each other, the adhesion tends to decrease at the interface between the metal terminals and the heat-fusible resin layers.

[0005] For this reason, an adhesive film may be disposed between the metal terminals and the heat-fusible resin layer for the purpose of enhancing their adhesion, etc. Examples of such an adhesive film include those described in Patent Document 1.

Prior Art Documents

Patent Documents

[0006]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0007] In recent years, with the increase in the capacity of power storage devices, the amount of gas generated from power storage device elements has tended to increase. When the internal pressure of the power storage device rises due to gas generation from the power storage device element, there is a problem that the adhesive film for metal terminals adhered to the exterior material for the power storage device is likely to peel off.

[0008] The present disclosure provides an adhesive film for a metal terminal interposed between a metal terminal electrically connected to an electrode of a power storage device element and an exterior material for a power storage device that seals the power storage device element, and the main object is to provide an adhesive film for a metal terminal that exhibits high sealing strength with the exterior material for a power storage device. Further, the present disclosure also aims to provide a method for manufacturing the adhesive film for a metal terminal, a metal terminal with the adhesive film for a metal terminal, an exterior material for a power storage device, a kit including the exterior material for a power storage device and the adhesive film for a metal terminal, a power storage device, and a method for manufacturing the power storage device.

Means for Solving the Problems

[0009] The inventors of the present disclosure conducted intensive studies to solve the above problems. As a result, the adhesive film for a metal terminal is composed of a laminate including at least a first polyolefin layer disposed on the surface on the side of the exterior material for a power storage device, a base material, and a second polyolefin layer disposed on the side of the metal terminal in this order. After setting the tensile elastic modulus of the adhesive film for a metal terminal to 700 MPa or less, further, among the layers located between the first polyolefin layer and the second polyolefin layer, when the layer having the highest Martens hardness measured in the direction perpendicular to the cross-section in the thickness direction of the layer is used as the base material, the absolute value of the difference between the Martens hardness measured in the direction perpendicular to the cross-section in the thickness direction of the base material and the Martens hardness measured in the direction perpendicular to the cross-section in the thickness direction of the first polyolefin layer is 10 N / mm 2 By setting it as follows, it was found that the adhesive film for a metal terminal exhibits high sealing strength with the exterior material for a power storage device. The present disclosure was completed by further repeating studies based on such findings. That is, the present disclosure provides an invention in the following aspects.

[0010] Namely, the present disclosure provides an adhesive film for a metal terminal interposed between a metal terminal electrically connected to an electrode of a power storage device element and an exterior material for a power storage device that seals the power storage device element, ​The adhesive film for metal terminals is composed of a laminate including, at least, a first polyolefin layer disposed on the surface on the side of the exterior material for the power storage device, a base material, and a second polyolefin layer disposed on the side of the metal terminals, in this order. The tensile elastic modulus of the adhesive film for metal terminals is 700 MPa or less. The base material is the layer among the layers positioned between the first polyolefin layer and the second polyolefin layer that has the greatest Martens hardness measured in a direction perpendicular to the cross-section in the thickness direction of the layer. The absolute value of the difference between the Martens hardness measured in a direction perpendicular to the cross-section in the thickness direction of the base material and the Martens hardness measured in a direction perpendicular to the cross-section in the thickness direction of the first polyolefin layer is 10 N / mm 2 or less. Adhesive film for metal terminals.

Advantages of the Invention

[0011] According to the present disclosure, there is provided an adhesive film for metal terminals interposed between a metal terminal electrically connected to an electrode of a power storage device element and an exterior material for a power storage device that seals the power storage device element, the adhesive film for metal terminals exhibiting high seal strength with the exterior material for a power storage device. Furthermore, it is also an object of the present disclosure to provide a method for manufacturing the adhesive film for metal terminals, a metal terminal with the adhesive film for metal terminals, an exterior material for a power storage device, a kit including the exterior material for a power storage device and the adhesive film for metal terminals, and a power storage device and a method for manufacturing the same.

Brief Description of the Drawings

[0012]

Figure 1

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Figure 4

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Figure 10

Embodiments for Carrying Out the Invention

[0013] The adhesive film for metal terminals of the present disclosure is an adhesive film for metal terminals interposed between a metal terminal electrically connected to an electrode of a power storage device element and an exterior material for a power storage device that seals the power storage device element. The adhesive film for metal terminals of the present disclosure is composed of a laminate including at least a first polyolefin layer disposed on the surface on the side of the exterior material for a power storage device, a base material, and a second polyolefin layer disposed on the side of the metal terminal, in this order. The tensile elastic modulus of the adhesive film for metal terminals is 700 MPa or less. The base material is the layer located between the first polyolefin layer and the second polyolefin layer and having the highest Martens hardness measured in a direction perpendicular to the cross-section in the thickness direction of the layer. In the adhesive film for metal terminals of the present disclosure, the absolute value of the difference between the Martens hardness measured in a direction perpendicular to the cross-section in the thickness direction of the base material and the Martens hardness measured in a direction perpendicular to the cross-section in the thickness direction of the first polyolefin layer is 10 N / mm 2 is as follows.

[0014] Since the adhesive film for metal terminals of the present disclosure has these characteristics, it can exhibit high sealing strength with the exterior material for power storage devices. More specifically, the adhesive film for metal terminals of the present disclosure is interposed between a metal terminal electrically connected to the electrode of a power storage device element and an exterior material for power storage devices that seals the power storage device element, and can exhibit high sealing strength with the heat-sealable resin layer of the exterior material for power storage devices.

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

[0016] Hereinafter, the adhesive film for metal terminals of the present disclosure, its manufacturing method, the power storage device, and its manufacturing method will be described in detail.

[0017] In this specification, for numerical ranges, the numerical range indicated by "~" means "above" and "below". For example, the notation of 2~15 mm means 2 mm or more and 15 mm or less. In the numerical ranges described step by step in the present disclosure, the upper limit value or the lower limit value described in a certain numerical range may be replaced with the upper limit value or the lower limit value of the numerical range described in other step-by-step descriptions. Further, the upper limit value and the upper limit value, the upper limit value and the lower limit value, or the lower limit value and the lower limit value described separately may be combined as numerical ranges, respectively. Also, in the numerical ranges described in the present disclosure, the upper limit value or the lower limit value described in a certain numerical range may be replaced with the value shown in the examples.

[0018] In addition, as a method for confirming the MD of the adhesive film for metal terminals, there is a method of observing the cross-section of the adhesive film for metal terminals (for example, the cross-section of the acid-modified polyolefin layer or the polyolefin layer) with an electron microscope to confirm the sea-island structure. In this method, the direction parallel to the cross-section where the average diameter of the shape of the islands in the direction perpendicular to the thickness direction of the adhesive film for metal terminals is the largest can be determined as the MD. Specifically, the cross-section in the length direction of the adhesive film for metal terminals and the directions obtained by changing the angle by 10 degrees each from the direction parallel to the cross-section in the length direction to the direction perpendicular to the cross-section in the length direction (a total of 10 cross-sections) are each observed with an electron microscope photograph to confirm the sea-island structure. Next, in each cross-section, the shape of each individual island is observed. Regarding the shape of each individual island, the straight-line distance connecting the leftmost end in the direction perpendicular to the thickness direction of the adhesive film for metal terminals and the rightmost end in the said perpendicular direction is defined as the diameter y. In each cross-section, the average of the top 20 diameters y in descending order of the diameter y of the island shape is calculated. The direction parallel to the cross-section where the average of the diameter y of the island shape is the largest is determined as the MD. Also, for example, the thermal shrinkage rate after leaving the adhesive film for metal terminals in a 150°C environment for 2 minutes can be measured, and the direction with the larger shrinkage rate can be determined as the MD.

[0019] 1. Adhesive Film for Metal Terminals The adhesive film for metal terminals of the present disclosure is interposed between a metal terminal electrically connected to the electrode of a power storage device element and an exterior material for a power storage device that seals the power storage device element. Specifically, for example, as shown in FIGS. 1 to 3, the adhesive film 1 for metal terminals of the present disclosure is interposed between a metal terminal 2 electrically connected to the electrode of a power storage device element 4 and an exterior material 3 for a power storage device that seals the power storage device element 4. Further, the metal terminal 2 protrudes outside the exterior material 3 for a power storage device and is sandwiched between the exterior material 3 for a power storage device and the adhesive film 1 for metal terminals at the peripheral edge 3a of the heat-sealed exterior material 3 for a power storage device.

[0020] In the present disclosure, the temporary adhesion process of the adhesive film for metal terminals to the metal terminals is performed, for example, under the conditions of a temperature of about 140 to 160°C, a pressure of about 0.01 to 1.0 MPa, a time of about 3 to 15 seconds, and a number of times of about 3 to 6 times. The main adhesion process is performed, for example, under the conditions of a temperature of about 160 to 240°C, a pressure of about 0.01 to 1.0 MPa, a time of about 3 to 15 seconds, and a number of times of about 1 to 3 times. Further, when heat-sealing the exterior material for the power storage device with the metal terminal having the adhesive film for metal terminals interposed therebetween, the heating temperature is usually in the range of about 180 to 210°C, the pressure is usually about 1.0 to 5.0 MPa, the time is about 1 to 5 seconds, and the number of times is about 1 time.

[0021] The adhesive film 1 for metal terminals of the present disclosure (hereinafter, may be simply referred to as "adhesive film") is provided to enhance the adhesion between the metal terminal 2 and the exterior material 3 for the power storage device. By enhancing the adhesion between the metal terminal 2 and the exterior material 3 for the power storage device, the sealing performance of the power storage device element 4 is improved. As described above, when heat-sealing the power storage device element 4, the metal terminal 2 electrically connected to the electrode of the power storage device element 4 protrudes outside the exterior material 3 for the power storage device, and the power storage device element is sealed. At this time, since the metal terminal 2 formed of metal and the heat-sealing resin layer 35 (a layer formed of a heat-sealing resin such as polyolefin) located in the innermost layer of the exterior material 3 for the power storage device are formed of different materials, if such an adhesive film is not used, the sealing performance of the power storage device element tends to be low at the interface between the metal terminal 2 and the heat-sealing resin layer 35.

[0022] Laminated Structure and Physical Properties of Adhesive Film for Metal Terminals The adhesive film for metal terminals of the present disclosure is composed of a laminate including at least a first polyolefin layer 12a, a base material 11, and a second polyolefin layer 12b, in this order from the side of the exterior material for the power storage device, as shown in FIGS. 4 to 7, for example. In the adhesive film 1 for metal terminals, the first polyolefin layer 12a constitutes the surface on the side of the exterior material for the power storage device. In the laminate constituting the adhesive film 1 for metal terminals of the present disclosure, with the base material 11 as a reference, the side of the first polyolefin layer 12a with respect to the base material 11 is the side of the exterior material for the power storage device, and the side of the second polyolefin layer 12b with respect to the base material 11 is the side of the metal terminal 2. The adhesive film 1 for metal terminals preferably has a structure of 3 to 6 layers.

[0023] As shown in FIG. 5, for example, the adhesive film 1 for metal terminals may include an adhesion promoter layer 13 on at least one of the interfaces between the base material 11 and the first polyolefin layer 12a and between the base material 11 and the second polyolefin layer 12b. By providing the adhesion promoter layer 13, the interfaces between the base material 11 and the first polyolefin layer 12a and between the base material 11 and the second polyolefin layer 12b can be adhered more firmly. FIG. 5 illustrates a laminated structure in which adhesion promoter layers 13 are provided between the base material 11 and the first polyolefin layer 12a and between the base material 11 and the second polyolefin layer 12b, respectively. Details of the adhesion promoter layer 13 will be described later.

[0024] In addition to the base material 11, the first polyolefin layer 12a, and the second polyolefin layer 12b, the adhesive film 1 for metal terminals may further include one or more resin layers (such as a third layer 12c, a fourth layer 12d, a fifth layer 12e, etc.). FIG. 6 illustrates a laminated structure including a third layer 12c between the base material 11 and the first polyolefin layer 12a and a fourth layer 12d between the base material 11 and the second polyolefin layer 12b. As described above, in the adhesive film 1 for metal terminals of the present disclosure, since the first polyolefin layer 12a constitutes the surface on the side of the exterior material for the power storage device, the resin layers such as the third layer 12c, the fourth layer 12d, and the fifth layer 12e are provided between the first polyolefin layer 12a and the base material 11 and / or on the side of the metal terminal 2 with respect to the base material 11.

[0025] Further, as shown in FIGS. 6 and 7, for example, the adhesive film 1 for metal terminals may include a colored layer 14 between the first polyolefin layer 12a and the second polyolefin layer 12b. The colored layer 14 is a layer in which the resin layer is colored with a colorant, and any layer between the first polyolefin layer 12a and the second polyolefin layer 12b may be the colored layer 14. For example, the base material 11, the adhesion promoter layer 13, and the resin layers (such as the third layer 12c, the fourth layer 12d, and the fifth layer 12e) can be the colored layer 14. FIG. 6 shows an example in which the base material 11 constitutes the colored layer 14, and FIG. 7 shows an example in which the third layer 12c provided between the base material 11 and the second polyolefin layer 12b constitutes the colored layer 14. The colored layer 14 included in the adhesive film 1 for metal terminals may be one layer or two or more layers.

[0026] Specific examples of the laminated structure of the adhesive film 1 for metal terminals are shown below. In the following laminated structures, at least one of the base material 11, the third layer 12c, the fourth layer 12d, the fifth layer 12e, and the adhesion promoter layer 13 may be colored (including a colorant) to form the colored layer 14. Also, at least one of the first polyolefin layer 12a and the second polyolefin layer 12b may be colored (including a colorant) to form the colored layer 14. · A laminated structure in which the first polyolefin layer 12a, the base material 11, and the second polyolefin layer 12b are laminated in this order · A laminated structure in which the first polyolefin layer 12a, the third layer 12c, the base material 11, and the second polyolefin layer 12b are laminated in this order · A laminated structure in which the first polyolefin layer 12a, the base material 11, the third layer 12c, and the second polyolefin layer 12b are laminated in this order · A laminated structure in which the first polyolefin layer 12a, the third layer 12c, the base material 11, the fourth layer 12d, and the second polyolefin layer 12b are laminated in this order · A laminated structure in which the first polyolefin layer 12a, the third layer 12c, the base material 11, the second polyolefin layer 12b, and the fourth layer 12d are laminated in this order · A laminated structure in which a first polyolefin layer 12a, a third layer 12c, a fourth layer 12d, a substrate 11, a fifth layer 12e, and a second polyolefin layer 12b are laminated in this order · A laminated structure in which a first polyolefin layer 12a, a third layer 12c, a substrate 11, a fourth layer 12d, a fifth layer 12e, and a second polyolefin layer 12b are laminated in this order · A laminated structure in which a first polyolefin layer 12a, a third layer 12c, a substrate 11, a fourth layer 12d, a second polyolefin layer 12b, and a fifth layer 12e are laminated in this order · A laminated structure in which a first polyolefin layer 12a, an adhesion promoter layer 13, a substrate 11, and a second polyolefin layer 12b are laminated in this order · A laminated structure in which a first polyolefin layer 12a, a substrate 11, an adhesion promoter layer 13, and a second polyolefin layer 12b are laminated in this order · A laminated structure in which a first polyolefin layer 12a, an adhesion promoter layer 13, a substrate 11, an adhesion promoter layer 13, and a second polyolefin layer 12b are laminated in this order

[0027] The tensile elastic modulus of the adhesive film for metal terminals of the present disclosure is 700 MPa or less. From the viewpoint of more preferably exerting the effects of the present disclosure, it is preferably about 650 MPa or less, more preferably about 600 MPa or less, still more preferably about 550 MPa or less. Also, as the lower limit, it is preferably about 300 MPa or more, more preferably about 350 MPa or more, still more preferably about 400 MPa or more. Preferred ranges include about 300 to 700 MPa, about 300 to 650 MPa, about 300 to 600 MPa, about 300 to 550 MPa, about 350 to 700 MPa, about 350 to 650 MPa, about 350 to 600 MPa, about 350 to 550 MPa, about 400 to 700 MPa, about 400 to 650 MPa, about 400 to 600 MPa, about 400 to 550 MPa, etc. The measuring method of the tensile elastic modulus of the adhesive film for metal terminals is as follows.

[0028] <Tensile Elastic Modulus> In accordance with the provisions of JIS K7161-1 (ISO527-1), the tensile elastic modulus of the sample (adhesive film for metal terminals) at 25°C is measured. Specifically, the sample is cut into a strip shape with a width (TD) of 15 mm and a length (MD) of 50 mm. Next, in an environment of 25°C, using a tensilon universal material testing machine, under the conditions of a tensile speed of 300 mm / min and a chuck distance of 30 mm, the stress-strain curve of the test piece of the sample is obtained, and the tensile elastic modulus of the sample is determined from the slope of the straight line connecting two points of strain 0.05% and 0.25%. Regarding the tensile elastic modulus of the base material, the colored layer, the first polyolefin layer, and the second polyolefin layer, the tensile elastic modulus is measured by preparing each layer as an independent layer and using it as the measurement target sample. The measurement is performed three times and the average value (N = 3) is adopted. If a sample with a width (TD) of 15 mm cannot be produced, the tensile elastic modulus is measured in the same manner for samples with different widths.

[0029] Furthermore, for the adhesive film 1 for metal terminals, the absolute value of the difference between the Martens hardness measured in a direction perpendicular to the cross-section in the thickness direction of the base material 11 and the Martens hardness measured in a direction perpendicular to the cross-section in the thickness direction of the first polyolefin layer 12a is 10 N / mm 2 or less. From the viewpoint of more preferably exerting the effects of the present disclosure, the absolute value of the difference from the Martens hardness is preferably about 9 N / mm 2 or less, more preferably about 8 N / mm 2 or less, still more preferably about 5 N / mm 2 or less, still more preferably about 3 N / mm 2 or less, and for the lower limit, for example, about 0 N / mm 2 or more, and the preferable range is 0 to 10 N / mm 2 or so, 0 to 9 N / mm 2 or so, 0 to 8 N / mm 2 or so, 0 to 5 N / mm 2 or so, 0 to 3 N / mm 2 or so, etc.

[0030] From the perspective of more preferably exerting the effects of the present disclosure, the absolute value of the difference between the tensile modulus of the base material 11 and the tensile modulus of the first polyolefin layer 12a of the adhesive film 1 for metal terminals is preferably about 400 MPa or less, more preferably about 350 MPa or less, still more preferably about 300 MPa or less, still more preferably about 200 MPa or less, still more preferably about 100 MPa or less. Also, regarding the lower limit, it is about 0 MPa or more, and preferable ranges include about 0 to 400 MPa, about 0 to 350 MPa, about 0 to 300 MPa, about 0 to 200 MPa, and about 0 to 100 MPa. The tensile modulus of the base material 11 is a value measured using the base material 11 as a sample in the measurement of the tensile modulus described in the <tensile modulus>.

[0031] Also, from the perspective of more preferably exerting the effects of the present disclosure, the value of the tensile modulus of the second polyolefin layer 12b of the adhesive film 1 for metal terminals is preferably equal to or less than the value of the tensile modulus of the base material 11. The tensile modulus of the second polyolefin layer 12b is a value measured using the second polyolefin layer 12b as a sample in the measurement of the tensile modulus described in the <tensile modulus>.

[0032] Further, from the viewpoint of more suitably exhibiting the effects of the present disclosure, in the adhesive film 1 for metal terminals, the absolute value of the difference between the tensile elastic modulus of the first polyolefin layer 12a and the tensile elastic modulus of the base material 11 is 300 MPa or less, the absolute value of the difference between the tensile elastic modulus of the second polyolefin layer 12b and the tensile elastic modulus of the base material 11 is 300 MPa or less, and further, the absolute value of the difference between the tensile elastic modulus of the first polyolefin layer 12a and the tensile elastic modulus of the second polyolefin layer 12b is preferably 300 MPa or less. Regarding the absolute value of the difference between the tensile elastic modulus of the first polyolefin layer 12a and the tensile elastic modulus of the base material 11, more preferably, it is about 250 MPa or less, still more preferably, it is about 200 MPa or less, and preferably, it is about 0 MPa or more. The preferable range is about 0 to 300 MPa, about 0 to 250 MPa, or about 0 to 200 MPa. Regarding the absolute value of the difference between the tensile elastic modulus of the second polyolefin layer 12b and the tensile elastic modulus of the base material 11, more preferably, it is about 250 MPa or less, still more preferably, it is about 200 MPa or less, and preferably, it is about 0 MPa or more, more preferably, it is about 5 MPa or more, still more preferably, it is about 10 MPa or more. The preferable range is about 0 to 300 MPa, about 0 to 250 MPa, about 0 to 200 MPa, about 5 to 300 MPa, about 5 to 250 MPa, about 5 to 200 MPa, about 10 to 300 MPa, about 10 to 250 MPa, or about 10 to 200 MPa. Regarding the absolute value of the difference between the tensile elastic modulus of the first polyolefin layer 12a and the tensile elastic modulus of the second polyolefin layer 12b, more preferably, it is about 250 MPa or less, still more preferably, it is about 200 MPa or less, and regarding the lower limit, it is about 0 MPa or more. The preferable range is about 0 to 300 MPa, about 0 to 250 MPa, or about 0 to 200 MPa. The tensile elastic modulus of the first polyolefin layer 12a is a value measured using the first polyolefin layer 12a as a sample in the measurement of the tensile elastic modulus described in the <Tensile Elastic Modulus>.

[0033] <Martens Hardness> In the present disclosure, the method for measuring the Martens hardness of each layer of the adhesive film 1 for metal terminals (for example, the base material 11, the first polyolefin layer 12a, the second polyolefin layer 12b, the colored layer 14, etc.) is as follows. Regarding the Martens hardness of each layer, the adhesive film 1 for metal terminals is used as a sample, and each layer in the state laminated on the sample is the measurement target. Specifically, as a pretreatment of the sample to be measured, the adhesive film 1 for metal terminals is cut into MD 30 mm and TD 15 mm. Next, the sample is embedded in an epoxy cold embedding resin and dried for about 1 day. Then, using a mechanical polishing device, it is polished in the direction parallel to the TD direction of the sample embedded in the resin to make the cross-section of the sample have a surface roughness of about 1.0 μm. As the measurement of the Martens hardness by the indentation method, the Martens hardness is measured in a direction perpendicular to the cross-section (the central part in the thickness direction) in the thickness direction of the layer to be measured.

[0034] [Measurement conditions for Martens hardness] The load is 25 mN. The load application acceleration is 25 mN / 20 s. The holding time is 5 s. The load unloading speed is 25 mN / 20 s. The indenter is a Vickers indenter with a face angle of 136° at the tip of a regular square pyramid. The measurement temperature is 25°C. The measured value is the average value of a total of 8 measured values obtained by measuring 10 times while changing the measurement location and excluding the maximum value and the minimum value.

[0035] From the perspective of more suitably achieving the effects of the present disclosure, the total thickness of the adhesive film 1 for metal terminals is, for example, about 50 μm or more, preferably about 80 μm or more, more preferably about 90 μm or more, and still more preferably about 100 μm or more. Also, the total thickness of the adhesive film 1 for metal terminals of the present disclosure is about 500 μm or less, preferably about 300 μm or less, more preferably about 250 μm or less, and still more preferably about 200 μm or less. Preferred ranges for the total thickness of the adhesive film 1 for metal terminals of the present disclosure include about 50 to 500 μm, about 50 to 300 μm, about 50 to 250 μm, about 50 to 200 μm, about 80 to 500 μm, about 80 to 300 μm, about 80 to 250 μm, about 80 to 200 μm, about 90 to 500 μm, about 90 to 300 μm, about 90 to 250 μm, about 90 to 200 μm, about 100 to 500 μm, about 100 to 300 μm, about 100 to 250 μm, and about 100 to 200 μm. As a more specific example, for instance, when the adhesive film 1 for metal terminals of the present disclosure is used in a relatively small power storage device for a mobile phone, smartphone, or tablet, the total thickness is preferably about 60 to 100 μm, and when used in a relatively large power storage device for a power storage system or in-vehicle use, the total thickness is preferably about 100 to 300 μm.

[0036] In the adhesive film 1 for metal terminals, the ratio of the total thickness of the first polyolefin layer 12a, the base material 11, the second polyolefin layer 12b, the adhesion promoter layer 13 provided as required, and the resin layer (the third layer 12c, the fourth layer 12d, the fifth layer 12e, etc.) provided as required to the thickness (total thickness) of the laminate constituting the adhesive film 1 for metal terminals is preferably 90% or more, more preferably 95% or more, and even more preferably 98% or more. As a specific example, when the adhesive film 1 for metal terminals of the present disclosure includes the first polyolefin layer 12a, the base material 11, and the second polyolefin layer 12b, the ratio of the total thickness of these layers to the thickness (total thickness) of the laminate constituting the adhesive film 1 for metal terminals is preferably 90% or more, more preferably 95% or more, and even more preferably 98% or more. Further, when the adhesive film 1 for metal terminals of the present disclosure includes the first polyolefin layer 12a, the base material 11, the second polyolefin layer 12b, and the third layer 12c, the ratio of the total thickness of these layers to the thickness (total thickness) of the laminate constituting the adhesive film 1 for metal terminals is preferably 90% or more, more preferably 95% or more, and even more preferably 98% or more. Further, when the adhesive film 1 for metal terminals of the present disclosure includes the first polyolefin layer 12a, the base material 11, the second polyolefin layer 12b, the third layer 12c, and the fourth layer 12d, the ratio of the total thickness of these layers to the thickness (total thickness) of the laminate constituting the adhesive film 1 for metal terminals is preferably 90% or more, more preferably 95% or more, and even more preferably 98% or more. Further, when the adhesive film 1 for metal terminals of the present disclosure includes the first polyolefin layer 12a, the base material 11, the second polyolefin layer 12b, the third layer 12c, the fourth layer 12d, and the fifth layer 12e, the ratio of the total thickness of these layers to the thickness (total thickness) of the laminate constituting the adhesive film 1 for metal terminals is preferably 90% or more, more preferably 95% or more, and even more preferably 98% or more.

[0037] Each Layer Forming the Adhesive Film for Metal Terminals [Base material 11] In the adhesive film 1 for metal terminals, the base material 11 is provided between the first polyolefin layer 12a and the second polyolefin layer 12b, and is a layer that functions as a support for the adhesive film 1 for metal terminals. As will be described later, the base material 11 can also be colored to form the colored layer 14 described later.

[0038] The base material 11 can be formed of, for example, a resin film. When the base material 11 is formed of a resin film, when manufacturing the adhesive film 1 for metal terminals of the present disclosure by laminating the base material 11 with the first polyolefin layer 12a, the second polyolefin layer 12b, etc., a pre-formed resin film may be used as the base material 11. Further, the resin forming the base material 11 may be formed into a film on the surfaces of the first polyolefin layer 12a, the second polyolefin layer 12b, etc. by extrusion molding, coating, etc., to form the base material 11 formed of a resin film.

[0039] The material for forming the base material 11 is not particularly limited. Examples of the material for forming the base material 11 include polyolefin resins, polyamide resins, polyester resins, epoxy resins, acrylic resins, fluorine resins, silicone resins, phenolic resins, polyetherimides, polyimides, polycarbonates, and mixtures and copolymers thereof. Among these, polyolefin resins are particularly preferred. That is, the material for forming the base material 11 is preferably a resin containing a polyolefin backbone such as polyolefin or acid-modified polyolefin. Whether the resin constituting the base material 11 contains a polyolefin backbone can be analyzed by, for example, infrared spectroscopy, gas chromatography-mass spectrometry, etc.

[0040] The base material 11 preferably contains a polyolefin resin, preferably contains a polyolefin, and is more preferably a layer formed of a polyolefin. The layer formed of a polyolefin may be a stretched polyolefin film or an unstretched polyolefin film, but an unstretched polyolefin film is preferred. Specific examples of the polyolefin include polyethylene such as low-density polyethylene, medium-density polyethylene, high-density polyethylene, and linear low-density polyethylene; crystalline or amorphous polypropylene such as homopolypropylene, block copolymers of polypropylene (e.g., block copolymers of propylene and ethylene), and random copolymers of polypropylene (e.g., random copolymers of propylene and ethylene); and terpolymers of ethylene-butene-propylene. Among these polyolefins, polyethylene and polypropylene are preferred, and polypropylene is more preferred. Further, since it has excellent electrolytic solution resistance, the base material 11 preferably contains homopolypropylene, is more preferably formed of homopolypropylene, and is even more preferably an unstretched homopolypropylene film.

[0041] Examples of polyamides include aliphatic polyamides such as nylon 6, nylon 66, nylon 610, nylon 12, nylon 46, and copolymers of nylon 6 and nylon 66; hexamethylenediamine-isophthalic acid-terephthalic acid copolymer polyamides such as nylon 6I, nylon 6T, nylon 6IT, and nylon 6I6T (where I represents isophthalic acid and T represents terephthalic acid), which contain structural units derived from terephthalic acid and / or isophthalic acid, and polyamides containing aromatics such as polymetaxylylene adipamide (MXD6); alicyclic polyamides such as polyaminomethylcyclohexyl adipamide (PACM6); furthermore, polyamides copolymerized with lactam components or isocyanate components such as 4,4'-diphenylmethane-diisocyanate, and polyester amide copolymers and polyether ester amide copolymers that are copolymers of copolyamides with polyesters or polyalkylene ether glycols; and these copolymers and the like. These polyamides may be used alone or in combination of two or more.

[0042] Examples of the polyester include polyethylene terephthalate, polybutylene terephthalate, polyethylene naphthalate, polybutylene naphthalate, polyethylene isophthalate, copolyester with ethylene terephthalate as the main repeating unit, copolyester with butylene terephthalate as the main repeating unit, etc. Examples of the copolyester with ethylene terephthalate as the main repeating unit specifically include a copolymer polyester obtained by polymerizing ethylene isophthalate with ethylene terephthalate as the main repeating unit (hereinafter abbreviated following polyethylene(terephthalate / isophthalate)), polyethylene(terephthalate / isophthalate), polyethylene(terephthalate / adipate), polyethylene(terephthalate / sodium sulfoisophthalate), polyethylene(terephthalate / sodium isophthalate), polyethylene(terephthalate / phenyl-dicarboxylate), polyethylene(terephthalate / decanedicarboxylate), etc. Examples of the copolyester with butylene terephthalate as the main repeating unit specifically include a copolymer polyester obtained by polymerizing butylene isophthalate with butylene terephthalate as the main repeating unit (hereinafter abbreviated following polybutylene(terephthalate / isophthalate)), polybutylene(terephthalate / adipate), polybutylene(terephthalate / sebacate), polybutylene(terephthalate / decanedicarboxylate), polybutylene naphthalate, etc. These polyesters may be used alone or in combination of two or more.

[0043] Examples of the method for adjusting the Martens hardness and tensile elastic modulus include the resin material to be selected, the resin formulation, the cooling conditions during film formation (the time until the resin extruded from the die is cooled to room temperature), the resin forming method (extrusion method, inflation method, etc.).

[0044] The base material 11 is the layer among the layers positioned between the first polyolefin layer 12a and the second polyolefin layer 12b, which has the largest Martens hardness measured in a direction perpendicular to the cross-section in the thickness direction of the layer.

[0045] The Martens hardness of the base material 11 is such that the absolute value of the difference between the Martens hardness measured in a direction perpendicular to the cross-section in the thickness direction of the base material 11 and the Martens hardness measured in a direction perpendicular to the cross-section in the thickness direction of the first polyolefin layer 12a is 10 N / mm 2 or less, and is not particularly limited. From the viewpoint of more preferably exerting the effects of the present disclosure, the Martens hardness of the base material 11 is preferably about 10 N / mm 2 or more, more preferably about 15 N / mm 2 or more, still more preferably about 20 N / mm 2 or more, and preferably about 40 N / mm 2 or less, more preferably about 35 N / mm 2 or less, still more preferably about 30 N / mm 2 or less, and the preferable range is about 10 to 40 N / mm 2 level, about 10 to 35 N / mm 2 level, about 10 to 30 N / mm 2 level, about 15 to 40 N / mm 2 level, about 15 to 35 N / mm 2 level, about 15 to 30 N / mm 2 level, about 20 to 40 N / mm 2 level, about 20 to 35 N / mm 2 level, about 20 to 30 N / mm 2 level can be mentioned.

[0046] Also, the tensile elastic modulus of the base material 11 is not particularly limited as long as the tensile elastic modulus of the adhesive film 1 for metal terminals is 700 MPa or less. From the viewpoint of more preferably exhibiting the effects of the present disclosure, the tensile elastic modulus of the base material 11 is preferably 820 MPa or less, more preferably 800 MPa or less, still more preferably 750 MPa or less, still more preferably 600 MPa or less, and is also preferably 250 MPa or more, more preferably 300 MPa or more, still more preferably 350 MPa or more. The preferable range is about 250 to 820 MPa, about 250 to 800 MPa, about 250 to 750 MPa, about 250 to 600 MPa, about 300 to 820 MPa, about 300 to 800 MPa, about 300 to 750 MPa, about 300 to 600 MPa, about 350 to 820 MPa, about 350 to 800 MPa, about 350 to 750 MPa, about 350 to 600 MPa.

[0047] The melting peak temperature of the base material 11 is preferably 120°C or higher, more preferably about 130°C or higher, still more preferably about 140°C or higher. From the same viewpoint, the melting peak temperature is, for example, about 210°C or lower, preferably about 200°C or lower, more preferably about 190°C or lower, still more preferably about 180°C or lower, still more preferably about 170°C or lower. The preferable range of the melting peak temperature is about 120 to 210°C, about 120 to 200°C, about 120 to 190°C, about 120 to 180°C, about 120 to 170°C, about 130 to 210°C, about 130 to 200°C, about 130 to 190°C, about 130 to 180°C, about 130 to 170°C, about 140 to 210°C, about 140 to 200°C, about 140 to 190°C, about 140 to 180°C, about 140 to 170°C. In the present disclosure, the melting peak temperature of the resin is a value measured by DSC.

[0048] The base material 11 may be a single layer or a multilayer.

[0049] Further, by blending a colorant into the base material 11, the base material 11 can also be made into a layer containing the colorant. When the base material 11 is a colored layer 14, the base material 11 is preferably a layer formed of a polyolefin resin containing a colorant.

[0050] Also, the base material 11 can select a resin with low transparency to adjust the light transmittance. When the base material 11 is a film, a colored film or a film with low transparency can also be used.

[0051] When the base material 11 is composed of a resin film, known adhesion means such as corona discharge treatment, ozone treatment, and plasma treatment may be applied to the surface of the base material 11 as necessary.

[0052] Also, from the viewpoint of more suitably achieving the effects of the present disclosure, the thickness of the base material 11 is preferably about 20 μm or more, more preferably about 30 μm or more, still more preferably about 40 μm or more, and is preferably about 120 μm or less, more preferably about 110 μm or less, still more preferably about 100 μm or less. Preferred ranges for the thickness of the base material 11 include about 20 to 120 μm, about 20 to 110 μm, about 20 to 100 μm, about 30 to 120 μm, about 30 to 110 μm, about 30 to 100 μm, about 40 to 120 μm, about 40 to 110 μm, and about 40 to 100 μm.

[0053] [First Polyolefin Layer 12a and Second Polyolefin Layer 12b] The first polyolefin layer 12a is a layer disposed on the surface of the adhesive film 1 for metal terminals on the side of the exterior material for the power storage device. That is, the first polyolefin layer 12a constitutes one surface of the adhesive film 1 for metal terminals. Also, the second polyolefin layer 12b is a layer disposed on the side of the metal terminal 2. The second polyolefin layer 12b does not necessarily constitute the other surface of the adhesive film 1 for metal terminals, but preferably constitutes the other surface of the adhesive film 1 for metal terminals.

[0054] When the adhesive film 1 for metal terminals of the present disclosure is disposed between the metal terminal 2 of the power storage device 10 and the exterior material 3 for the power storage device, the surface of the metal terminal 2 made of metal and the heat-sealable resin layer 35 (a layer formed of a heat-sealable resin such as polyolefin) of the exterior material 3 for the power storage device are adhered via the adhesive film 1 for metal terminals. The first polyolefin layer 12a of the adhesive film 1 for metal terminals is disposed on the side of the exterior material 3 for the power storage device, the second polyolefin layer 12b is disposed on the side of the metal terminal 2, the first polyolefin layer 12a is in close contact with the heat-sealable resin layer 35 of the exterior material 3 for the power storage device, and the side of the second polyolefin layer 12b is in close contact with the metal terminal. The first polyolefin layer 12a may be a single layer or a multilayer. Also, the second polyolefin layer 12b may be a single layer or a multilayer.

[0055] The first polyolefin layer 12a and the second polyolefin layer 12b can each be formed of, for example, a resin film. When the first polyolefin layer 12a and the second polyolefin layer 12b are each formed of a resin film, when manufacturing the adhesive film 1 for metal terminals of the present disclosure by laminating the first polyolefin layer 12a and the second polyolefin layer 12b with a base material 11 or the like, the pre-formed resin films may be used as the first polyolefin layer 12a and the second polyolefin layer 12b, respectively. Also, the resins forming the first polyolefin layer 12a and the second polyolefin layer 12b may each be formed into a film on the surface of a base material 11 or the like by extrusion molding, coating, or the like to form the first polyolefin layer 12a and the second polyolefin layer 12b formed of a resin film.

[0056] The first polyolefin layer 12a and the second polyolefin layer 12b can each be composed of a resin. Examples of the resin constituting the first polyolefin layer 12a and the second polyolefin layer 12b include polyolefin resins, polyamide resins, polyester resins, epoxy resins, acrylic resins, fluororesins, silicone resins, phenolic resins, polyetherimides, polyimides, polycarbonates, and mixtures and copolymers thereof. Among these, polyolefin resins are particularly preferred.

[0057] Examples of the polyolefin resin include polyolefins and acid-modified polyolefins.

[0058] Specific examples of the polyolefin include polyethylene such as low-density polyethylene, medium-density polyethylene, high-density polyethylene, and linear low-density polyethylene; crystalline or amorphous polypropylene such as homopolypropylene, block copolymers of polypropylene (e.g., block copolymers of propylene and ethylene), and random copolymers of polypropylene (e.g., random copolymers of propylene and ethylene); and terpolymers of ethylene-butene-propylene. Among these polyolefins, polyethylene and polypropylene are preferably used, and polypropylene is more preferably used.

[0059] Also, the acid-modified polyolefin is not particularly limited as long as it is an acid-modified polyolefin, but preferably includes a polyolefin graft-modified with an unsaturated carboxylic acid or its anhydride. Examples of the carboxylic acid or its anhydride used for acid modification include maleic acid, acrylic acid, itaconic acid, crotonic acid, maleic anhydride, and itaconic anhydride. It is preferable that a peak derived from maleic anhydride is detected when the resin layer containing maleic anhydride is analyzed by infrared spectroscopy. For example, when measuring maleic anhydride-modified polyolefin by infrared spectroscopy, around a wave number of 1760 cm -1 and around a wave number of 1780 cm -1A peak derived from maleic anhydride is detected in the vicinity. When it is a layer composed of maleic anhydride-modified polyolefin, a peak derived from maleic anhydride is detected by infrared spectroscopy. However, if the degree of acid modification is low, the peak may become small and undetectable. In that case, it can be analyzed by nuclear magnetic resonance spectroscopy. Examples of the polyolefin to be acid-modified are the same polyolefins as described above. Similarly, polyethylene and polypropylene are preferably mentioned, and polypropylene is more preferably mentioned.

[0060] The first polyolefin layer 12a disposed on the side of the exterior material 3 for the power storage device preferably contains a polyolefin as a main component, and more preferably contains polypropylene as a main component. Here, the main component means a resin component having a content of, for example, 50% by mass or more, preferably 60% by mass or more, more preferably 70% by mass or more, further preferably 80% by mass or more, further preferably 90% by mass or more, further preferably 95% by mass or more, further preferably 98% by mass or more, and further preferably 99% by mass or more among the resin components contained in the first polyolefin layer 12a. For example, when the first polyolefin layer 12a contains polypropylene as a main component, it means that the content of polypropylene among the resin components contained in the first polyolefin layer 12a is, for example, 50% by mass or more, preferably 60% by mass or more, more preferably 70% by mass or more, further preferably 80% by mass or more, further preferably 90% by mass or more, further preferably 95% by mass or more, further preferably 98% by mass or more, and further preferably 99% by mass or more.

[0061] Further, the second polyolefin layer 12b disposed on both sides of the metal terminal 2 more preferably contains an acid-modified polyolefin as a main component, and even more preferably contains an acid-modified polypropylene as a main component. Here, the main component means that among the resin components contained in the second polyolefin layer 12b, the content rate is, for example, 50% by mass or more, preferably 60% by mass or more, more preferably 70% by mass or more, even more preferably 80% by mass or more, even more preferably 90% by mass or more, even more preferably 95% by mass or more, even more preferably 98% by mass or more, and even more preferably 99% by mass or more of the resin component. For example, that the second polyolefin layer 12b contains an acid-modified polypropylene as a main component means that among the resin components contained in the second polyolefin layer 12b, the content rate of the acid-modified polypropylene is, for example, 50% by mass or more, preferably 60% by mass or more, more preferably 70% by mass or more, even more preferably 80% by mass or more, even more preferably 90% by mass or more, even more preferably 95% by mass or more, even more preferably 98% by mass or more, and even more preferably 99% by mass or more.

[0062] From the viewpoint of more preferably exerting the effects of the present disclosure, the Martens hardness of the first polyolefin layer 12a is preferably about 35 N / mm 2 or less, more preferably about 30 N / mm 2 or less, even more preferably about 25 N / mm 2 or less, and preferably about 10 N / mm 2 or more, more preferably about 15 N / mm 2 or more, even more preferably about 20 N / mm 2 or more, and the preferable range is from 10 to 35 N / mm 2 or so, from 10 to 30 N / mm 2 or so, from 10 to 25 N / mm 2 or so, from 15 to 35 N / mm 2 or so, from 15 to 30 N / mm 2 or so, from 15 to 25 N / mm 2 or so, from 20 to 35 N / mm 2 or so, from 20 to 30 N / mm 2 or so, from 20 to 25 N / mm 2Examples of the degree include.

[0063] From the viewpoint of more preferably exhibiting the effects of the present disclosure, the Martens hardness of the second polyolefin layer 12b is preferably about 35 N / mm 2 or less, more preferably about 30 N / mm 2 or less, still more preferably about 25 N / mm 2 or less, and preferably about 10 N / mm 2 or more, more preferably about 15 N / mm 2 or more, still more preferably about 20 N / mm 2 or more, and the preferable range is about 10 to 35 N / mm 2 level, about 10 to 30 N / mm 2 level, about 10 to 25 N / mm 2 level, about 15 to 35 N / mm 2 level, about 15 to 30 N / mm 2 level, about 15 to 25 N / mm 2 level, about 20 to 35 N / mm 2 level, about 20 to 30 N / mm 2 level, about 20 to 25 N / mm 2 Examples of the degree include.

[0064] Also, from the viewpoint of more preferably exhibiting the effects of the present disclosure, the tensile elastic modulus of the first polyolefin layer 12a is not particularly limited as long as the tensile elastic modulus of the adhesive film 1 for metal terminals is 700 MPa or less. From the viewpoint of more preferably exhibiting the effects of the present disclosure, the tensile elastic modulus of the first polyolefin layer 12a is preferably 700 MPa or less, more preferably 600 MPa or less, still more preferably 500 MPa or less, and preferably 100 MPa or more, more preferably 150 MPa or more, still more preferably 200 MPa or more. The preferable range includes about 100 to 700 MPa, about 100 to 600 MPa, about 100 to 500 MPa, about 150 to 700 MPa, about 150 to 600 MPa, about 150 to 500 MPa, about 200 to 700 MPa, about 200 to 600 MPa, and about 200 to 500 MPa.

[0065] Also, from the perspective of more preferably exhibiting the effects of the present disclosure, the tensile modulus of the second polyolefin layer 12b is not particularly limited as long as the tensile modulus of the adhesive film 1 for metal terminals is 700 MPa or less. From the perspective of more preferably exhibiting the effects of the present disclosure, the tensile modulus of the second polyolefin layer 12b is preferably 700 MPa or less, more preferably 600 MPa or less, still more preferably 500 MPa or less, and is also preferably 100 MPa or more, more preferably 150 MPa or more, still more preferably 200 MPa or more. Preferred ranges include about 100 to 700 MPa, about 100 to 600 MPa, about 100 to 500 MPa, about 150 to 700 MPa, about 150 to 600 MPa, about 150 to 500 MPa, about 200 to 700 MPa, about 200 to 600 MPa, and about 200 to 500 MPa.

[0066] The melting peak temperatures of the first polyolefin layer 12a and the second polyolefin layer 12b are each preferably about 125°C or higher, more preferably about 130°C or higher, still more preferably about 135°C or higher. The melting peak temperature is, for example, about 180°C or lower, preferably about 175°C or lower, more preferably about 170°C or lower, still more preferably about 165°C or lower, and still more preferably about 160°C or lower. Preferred ranges of the melting peak temperature include about 125 to 180°C, about 125 to 175°C, about 125 to 170°C, about 125 to 165°C, about 125 to 160°C, about 130 to 180°C, about 130 to 175°C, about 130 to 170°C, about 130 to 165°C, about 130 to 160°C, about 135 to 180°C, about 135 to 175°C, about 135 to 170°C, about 135 to 165°C, and about 135 to 160°C.

[0067] Also, the thicknesses of the first polyolefin layer 12a and the second polyolefin layer 12b are each preferably about 10 μm or more, more preferably about 15 μm or more, still more preferably about 20 μm or more, and are preferably about 120 μm or less, more preferably about 100 μm or less, still more preferably about 80 μm or less. Preferred ranges include about 10 to 120 μm, about 10 to 100 μm, about 10 to 80 μm, about 15 to 120 μm, about 15 to 100 μm, about 15 to 80 μm, about 20 to 120 μm, about 20 to 100 μm, and about 20 to 80 μm.

[0068] The first polyolefin layer 12a and the second polyolefin layer 12b contain known colorants (such as pigments), similar to the colorant layer 14, and may constitute the colorant layer 14. The types and addition amounts of the pigments are the same as those of the colorant layer 14 described later.

[0069] Also, for example, the first polyolefin layer 12a and the second polyolefin layer 12b may each contain a filler as needed. When the first polyolefin layer 12a and the second polyolefin layer 12b contain a filler, the filler functions as a spacer, so that it is possible to effectively suppress a short circuit between the metal terminal 2 and the barrier layer 33 of the exterior material 3 for the power storage device. The particle size of the filler is in the range of about 0.1 to 35 μm, preferably about 5.0 to 30 μm, and more preferably about 10 to 25 μm. Also, the content of the filler is about 5 to 30 parts by mass, more preferably about 10 to 20 parts by mass, respectively, based on 100 parts by mass of the resin component forming the first polyolefin layer 12a and the second polyolefin layer 12b.

[0070] As the filler, either an inorganic or an organic filler can be used. Examples of the inorganic filler include carbon (carbon, graphite), silica, aluminum oxide, barium titanate, iron oxide, silicon carbide, zirconium oxide, zirconium silicate, magnesium oxide, titanium oxide, calcium aluminate, calcium hydroxide, aluminum hydroxide, magnesium hydroxide, calcium carbonate, and the like. Examples of the organic filler include fluororesin, phenol resin, urea resin, epoxy resin, acrylic resin, benzoguanamine-formaldehyde condensate, melamine-formaldehyde condensate, polymethyl methacrylate cross-linked product, polyethylene cross-linked product, and the like. From the viewpoints of shape stability, rigidity, and resistance to the content, aluminum oxide, silica, fluororesin, acrylic resin, and benzoguanamine-formaldehyde condensate are preferable, and among them, spherical aluminum oxide and silica are more preferable. As a method for mixing the filler into the resin components forming the first polyolefin layer 12a and the second polyolefin layer 12b, a method of melt-blending both in a Banbury mixer or the like in advance to form a masterbatch and then adjusting it to a predetermined mixing ratio, a method of directly mixing with the resin components, and the like can be adopted.

[0071] [Resin layer (the third layer 12c, the fourth layer 12d, the fifth layer 12e, etc.)] In addition to the base material 11, the first polyolefin layer 12a, and the second polyolefin layer 12b, the adhesive film 1 for metal terminals may further include one or more resin layers such as the third layer 12c, the fourth layer 12d, and the fifth layer 12e, if necessary.

[0072] FIG. 6 illustrates a laminated structure including the third layer 12c between the base material 11 and the first polyolefin layer 12a and the fourth layer 12d between the base material 11 and the second polyolefin layer 12b. As described above, in the adhesive film 1 for metal terminals of the present disclosure, since the first polyolefin layer 12a constitutes the surface on the side of the exterior material for the power storage device, the resin layers such as the third layer 12c and the fourth layer 12d are provided between the first polyolefin layer 12a and the base material 11 and on the side of the metal terminal 2 rather than the base material 11.

[0073] In the present disclosure, when there is only one resin layer, the resin layer is denoted as the third layer 12c. When there are two resin layers, these layers are denoted as the third layer 12c and the fourth layer 12d. When there are three resin layers, these layers are denoted as the third layer 12c, the fourth layer 12d, and the fifth layer 12e. Even when there are four or more resin layers, the numerical values are increased and expressed as the sixth layer, the seventh layer, etc. accordingly.

[0074] The resin layers such as the third layer 12c, the fourth layer 12d, and the fifth layer 12e can each be formed of, for example, a resin film. When each of these resin layers is formed of a resin film, when manufacturing the adhesive film 1 for metal terminals of the present disclosure by laminating the resin layers such as the third layer 12c, the fourth layer 12d, and the fifth layer 12e with the base material 11 etc., the previously formed resin films can each be used as these resin layers. Also, the resin for forming the resin layers such as the third layer 12c, the fourth layer 12d, and the fifth layer 12e can each be formed into a film on the surface of the base material 11 etc. by extrusion molding, coating, etc., and used as a resin layer formed of a resin film etc.

[0075] The resin layers such as the third layer 12c, the fourth layer 12d, and the fifth layer 12e are each composed of a resin. Examples of the resin constituting the resin layer include polyolefin resins, polyamide resins, polyester resins, epoxy resins, acrylic resins, fluorine resins, silicone resins, phenol resins, polyetherimides, polyimides, polycarbonates, and mixtures and copolymers thereof. Among these, polyolefin resins are particularly preferred.

[0076] Examples of the polyolefin resin are the same as the polyolefin and acid-modified polyolefin exemplified in the first polyolefin layer 12a and the second polyolefin layer 12b.

[0077] The resin layer more preferably contains a polyolefin as a main component, and even more preferably contains polypropylene as a main component. Here, the main component means a resin component having a content of, for example, 50% by mass or more, preferably 60% by mass or more, more preferably 70% by mass or more, even more preferably 80% by mass or more, even more preferably 90% by mass or more, even more preferably 95% by mass or more, even more preferably 98% by mass or more, and even more preferably 99% by mass or more among the resin components contained in the resin layer. For example, when the resin layer contains polypropylene as a main component, it means that the content of polypropylene among the resin components contained in the resin layer is, for example, 50% by mass or more, preferably 60% by mass or more, more preferably 70% by mass or more, even more preferably 80% by mass or more, even more preferably 90% by mass or more, even more preferably 95% by mass or more, even more preferably 98% by mass or more, and even more preferably 99% by mass or more.

[0078] When the resin layer constitutes the surface on the side of the metal terminal 2, the resin layer more preferably contains an acid-modified polyolefin as a main component, and even more preferably contains acid-modified polypropylene as a main component. Here, the main component means a resin component having a content of, for example, 50% by mass or more, preferably 60% by mass or more, more preferably 70% by mass or more, even more preferably 80% by mass or more, even more preferably 90% by mass or more, even more preferably 95% by mass or more, even more preferably 98% by mass or more, and even more preferably 99% by mass or more among the resin components contained in the resin layer. For example, when the resin layer contains acid-modified polypropylene as a main component, it means that the content of acid-modified polypropylene among the resin components contained in the resin layer is, for example, 50% by mass or more, preferably 60% by mass or more, more preferably 70% by mass or more, even more preferably 80% by mass or more, even more preferably 90% by mass or more, even more preferably 95% by mass or more, even more preferably 98% by mass or more, and even more preferably 99% by mass or more.

[0079] From the perspective of more suitably exerting the effects of the present disclosure, the Martens hardness of resin layers such as the third layer 12c, the fourth layer 12d, and the fifth layer 12e is preferably about 35 N / mm 2 or less more preferably about 30 N / mm 2 or less, even more preferably about 25 N / mm 2 or less, and preferably about 10 N / mm 2 or more, more preferably about 15 N / mm 2 or more, even more preferably about 20 N / mm 2 or more, and the preferable range is 10 to 35 N / mm 2 or so, 10 to 30 N / mm 2 or so, 10 to 25 N / mm 2 or so, 15 to 35 N / mm 2 or so, 1 5 to 30 N / mm 2 or so, 15 to 25 N / mm 2 or so, 20 to 35 N / mm 2 or so, 20 to 30 N / mm 2 or so, 20 to 25 N / mm 2 or so can be mentioned. However, as described above, among the layers located between the first polyolefin layer 12a and the second polyolefin layer 12b, the layer with the highest Martens hardness measured in the direction perpendicular to the cross-section in the thickness direction of the layer is the base material 11.

[0080] Also, from the perspective of more preferably exerting the effects of the present disclosure, the tensile elastic modulus of resin layers such as the third layer 12c, the fourth layer 12d, and the fifth layer 12e is not particularly limited as long as the tensile elastic modulus of the adhesive film 1 for metal terminals is 700 MPa or less. From the perspective of more preferably exerting the effects of the present disclosure, the tensile elastic modulus of the third layer 12c, the fourth layer 12d, the fifth layer 12e, etc. is preferably about 700 MPa or less, more preferably about 600 MPa or less, still more preferably about 500 MPa or less, respectively, and is preferably about 100 MPa or more, more preferably about 150 MPa or more, still more preferably about 200 MPa or more. Preferred ranges include about 100 to 700 MPa, about 100 to 600 MPa, about 100 to 500 MPa, about 150 to 700 MPa, about 150 to 600 MPa, about 150 to 500 MPa, about 200 to 700 MPa, about 200 to 600 MPa, about 200 to 500 MPa.

[0081] The melting peak temperature of resin layers such as the third layer 12c, the fourth layer 12d, and the fifth layer 12e is preferably about 125°C or higher, more preferably about 130°C or higher, still more preferably about 135°C or higher, respectively. The melting peak temperature is, for example, about 180°C or lower, preferably about 175°C or lower, more preferably about 170°C or lower, still more preferably about 165°C or lower, still more preferably about 160°C or lower. Preferred ranges of the melting peak temperature include about 125 to 180°C, about 125 to 175°C, about 125 to 170°C, about 125 to 165°C, about 125 to 160°C, about 130 to 180°C, about 130 to 175°C, about 130 to 170°C, about 130 to 165°C, about 130 to 160°C, about 135 to 180°C, about 135 to 175°C, about 135 to 170°C, about 135 to 165°C, about 135 to 160°C.

[0082] Also, the thicknesses of the resin layers such as the third layer 12c, the fourth layer 12d, and the fifth layer 12e are each preferably about 10 μm or more, more preferably about 15 μm or more, still more preferably about 20 μm or more, and are also preferably about 120 μm or less, more preferably about 100 μm or less, still more preferably about 80 μm or less. Preferred ranges include about 10 to 120 μm, about 10 to 100 μm, about 10 to 80 μm, about 15 to 120 μm, about 15 to 100 μm, about 15 to 80 μm, about 20 to 120 μm, about 20 to 100 μm, and about 20 to 80 μm.

[0083] The resin layers such as the third layer 12c, the fourth layer 12d, and the fifth layer 12e contain known colorants (such as pigments), similar to the coloring layer 14, and may constitute the coloring layer 14. The types and addition amounts of the pigments are the same as those of the coloring layer 14 described later.

[0084] Also, the resin layers such as the third layer 12c, the fourth layer 12d, and the fifth layer 12e may contain fillers, similar to the first polyolefin layer 12a and the second polyolefin layer 12b. The types and addition amounts of the fillers are the same as those of the aforementioned first polyolefin layer 12a and second polyolefin layer 12b.

[0085] [Coloring layer 14] The coloring layer 14 of the present disclosure will be described. In the present disclosure, the coloring layer 14 is a colored layer. In the present disclosure, the coloring layer 14 can be provided, for example, between the first polyolefin layer 12a and the second polyolefin layer 12b of the adhesive film 1 for metal terminals. The coloring layer 14 is a resin layer colored with a colorant. For example, any layer between the first polyolefin layer 12a and the second polyolefin layer 12b can be used as the coloring layer 14, and the base material 11, the adhesion promoter layer 13, and the resin layers (such as the third layer 12c, the fourth layer 12d, and the fifth layer 12e) can become the coloring layer 14. FIG. 6 shows an example in which the base material 11 constitutes the coloring layer 14, and FIG. 7 shows an example in which the third layer 12c constitutes the coloring layer 14. The coloring layer 14 contained in the adhesive film 1 for metal terminals may be one layer or two or more layers.

[0086] It is preferable that the adhesive film 1 for metal terminals includes a colored layer 14 between the second polyolefin layer 12b and the base material 11. Further, it is also preferable to provide the colored layer 14 between the first polyolefin layer 12a and the base material 11. Further, it is also preferable to use the base material 11 as the colored layer 14.

[0087] The colored layer 14 is preferably a layer formed of a polyolefin resin containing a colorant. Examples of the polyolefin resin are the same as those exemplified for the first polyolefin layer 12a and the second polyolefin layer 12b.

[0088] The colored layer 14 may be formed of a single resin component alone, or may be formed of a blend polymer in which two or more resin components are combined.

[0089] The colorant is not particularly limited, and a colorant capable of coloring the resin layer can be preferably used. Specific examples of the colorant include pigments. As the pigment, various inorganic or organic pigments can be used. Specific examples of the pigment include carbon (carbon, graphite), silica, titanium oxide, iron oxide, zinc oxide, magnesium oxide, calcium oxide, titanium nitride, zirconia black, copper oxide, cobalt oxide, barium sulfate and other inorganic oxides, and quinacridone pigments, polyazo pigments, isoindolinone pigments and other organic pigments can be preferably exemplified. Carbon (carbon, graphite) is a material generally used inside a power storage device and has no risk of elution into the electrolytic solution. Further, a sufficient coloring effect can be obtained with an addition amount that is large enough to have a coloring effect and does not inhibit the adhesiveness, does not melt with heat, and can increase the apparent melt viscosity of the added resin. Furthermore, it can prevent the pressure-applied portion from becoming thin during heat adhesion (heat sealing), and can impart excellent sealing performance between the exterior material for the power storage device and the metal terminal.

[0090] The color of the colored layer 14 is not particularly limited and can be selected according to the purpose. The colored layer 14 is preferably, for example, black, gray, or white.

[0091] When adding a pigment to the coloring layer 14, for example, when using carbon black with a particle size of about 0.03 μm, the addition amount is about 0.05 to 0.3 parts by mass, preferably about 0.1 to 0.2 parts by mass, respectively, based on 100 parts by mass of the resin component forming the coloring layer 14. By adding a pigment to the coloring layer 14, the presence or absence of the adhesive film 1 for metal terminals can be made detectable by a sensor or inspectable visually. When adding the aforementioned filler and pigment to the coloring layer 14, the filler and pigment may be added to the same coloring layer 14, but from the viewpoint of not inhibiting the heat fusion property of the adhesive film 1 for metal terminals, it is preferable to add the filler and pigment separately in a plurality of layers.

[0092] From the viewpoint of more suitably exhibiting the effects of the present disclosure, a coloring layer 14 is provided between the first polyolefin layer 12a and the second polyolefin layer 12b, and the difference between the martens hardness of the base material 11 and the martens hardness of the coloring layer 14 is preferably about 10 N / mm 2 or less, more preferably about 8 N / mm 2 or less, and even more preferably about 5 N / mm 2 or less. Regarding the lower limit, for example, it is 0 N / mm 2 and the preferable range is 0 to 10 N / mm 2 or so, 0 to 8 N / mm 2 or so, 0 to 5 N / mm 2 or so.

[0093] From the viewpoint of more preferably exerting the effects of the present disclosure, the ratio of the thickness of the colored layer 14 of the adhesive film 1 for metal terminals to the thickness of the adhesive film 1 for metal terminals is preferably about 0.30 or less, more preferably about 0.25 or less, still more preferably about 0.20 or less, and also preferably about 0.01 or more, more preferably about 0.03 or more, still more preferably about 0.05 or more. Also, as a preferable range, it is about 0.01 to 0.30, about 0.01 to 0.25, about 0.01 to 0.20, about 0.03 to 0.30, about 0.03 to 0.25, about 0.03 to 0.20, about 0.05 to 0.30, about 0.05 to 0.25, about 0.05 to 0.20.

[0094] From the viewpoint of more preferably achieving the effects of the present disclosure, the thickness of the colored layer 14 is preferably about 50 μm or less, more preferably about 45 μm or less, still more preferably about 40 μm or less, even more preferably about 35 μm or less, still more preferably about 30 μm or less, and also preferably about 3 μm or more, more preferably about 5 μm or more, still more preferably about 10 μm or more. As a preferable range, it is preferably about 3 to 50 μm, about 3 to 45 μm, about 3 to 40 μm, about 3 to 35 μm, about 3 to 30 μm, about 5 to 50 μm, about 5 to 45 μm, about 5 to 40 μm, about 5 to 35 μm, about 5 to 30 μm, about 10 to 50 μm, about 10 to 45 μm, about 10 to 40 μm, about 10 to 35 μm, about 10 to 30 μm.

[0095] The colored layer 14 may contain known additives as necessary. The types and addition amounts of the fillers are the same as those of the first polyolefin layer 12a and the second polyolefin layer 12b.

[0096] [Adhesion promoter layer 13] Next, the adhesion promoter layer 13 is a layer provided as necessary for the purpose of firmly adhering, for example, the base material 11 and the first polyolefin layer 12a, and the base material 11 and the second polyolefin layer 12b (see FIG. 5). The adhesion promoter layer 13 may be provided only on one side between the base material 11 and the first polyolefin layer 12a and the second polyolefin layer 12b, or may be provided on both sides.

[0097] The adhesion promoter layer 13 can be formed using known adhesion promoters such as isocyanate-based, polyethyleneimine-based, polyester-based, polyurethane-based, and polybutadiene-based. From the viewpoint of obtaining strong adhesion strength, among these, it is preferably formed of an isocyanate-based adhesion promoter. As the isocyanate-based adhesion promoter, those composed of an isocyanate component selected from triisocyanate monomers and polymeric MDI are excellent in laminate strength and have little decrease in laminate strength at high temperatures. In particular, it is particularly preferable to form it with an adhesion promoter composed of triphenylmethane-4,4',4''-triisocyanate which is a triisocyanate monomer or polymethylene polyphenyl polyisocyanate which is polymeric MDI (NCO content is about 30%, viscosity is 200 to 700 mPa·s). Also, it is also preferable to form it with tris(p-isocyanatophenyl) thiophosphate which is a triisocyanate monomer or a two-component curable adhesion promoter having a polyethyleneimine-based main agent and polycarbodiimide as a crosslinking agent.

[0098] The adhesion promoter layer 13 can be formed by coating and drying using a known coating method such as a bar coating method, a roll coating method, or a gravure coating method. As the coating amount of the adhesion promoter, in the case of an adhesion promoter composed of triisocyanate, it is about 20 to 100 mg / m 2 preferably or about 40 to 60 mg / m 2 and in the case of an adhesion promoter composed of polymeric MDI it is about 40 to 150 mg / m 2 preferably 60 to 100 mg / m 2In the case of a two-component curable adhesion promoter containing a polyethyleneimine-based resin as the main component and polycarbodiimide as the crosslinking agent, it is 5 to 50 mg / m 2 level, preferably 10 to 30 mg / m 2 level. The triisocyanate monomer is a monomer having three isocyanate groups in one molecule, and polymeric MDI is a mixture of MDI and MDI oligomers polymerized from MDI, and is represented by the following formula.

[0099] [Chemical formula]

[0100] From the viewpoint of more preferably exhibiting the effects of the present invention, it is preferable that the first polyolefin layer 12a is in contact with the base material 11, and the second polyolefin layer 12b is in contact with the base material 11.

[0101] The adhesive film 1 for metal terminals of the present disclosure is preferably entirely formed of a polyolefin-based resin. For example, the resin component contained in the adhesive film 1 for metal terminals of the present disclosure is preferably only a polyolefin-based resin, more preferably only an acid-modified polyolefin and a polyolefin, and even more preferably only an acid-modified polypropylene and a polypropylene. Preferred acid-modified polyolefins and polyolefins are as described above.

[0102] The method of interposing the adhesive film 1 for metal terminals between the metal terminal 2 and the exterior material 3 for the power storage device is not particularly limited. For example, as shown in FIGS. 1 to 3, at the portion where the metal terminal 2 is sandwiched by the exterior material 3 for the power storage device, the adhesive film 1 for metal terminals may be wound around the metal terminal 2. Further, although not shown, at the portion where the metal terminal 2 is sandwiched by the exterior material 3 for the power storage device, the adhesive film 1 for metal terminals may be disposed on both sides of the metal terminal 2 so as to cross the two metal terminals 2.

[0103] [Metal terminal 2] The adhesive film 1 for metal terminals of the present disclosure is used by being interposed between the metal terminal 2 and the exterior material 3 for the power storage device. The metal terminal 2 (tab) is a conductive member electrically connected to the electrode (positive electrode or negative electrode) of the power storage device element 4 and is made of a metal material. The metal material constituting the metal terminal 2 is not particularly limited, and examples thereof include aluminum, nickel, copper, and the like. For example, the metal terminal 2 connected to the positive electrode of the lithium ion power storage device is usually made of aluminum or the like. Also, the metal terminal 2 connected to the negative electrode of the lithium ion power storage device is usually made of copper, nickel, or the like.

[0104] From the viewpoint of enhancing the electrolytic solution resistance, the surface of the metal terminal 2 is preferably subjected to a forming treatment. For example, when the metal terminal 2 is formed of aluminum, specific examples of the forming treatment include known methods for forming a corrosion-resistant film such as a phosphate, a chromate, a fluoride, and a triazine thiol compound. Among the methods for forming a corrosion-resistant film, a phosphating treatment using a composition composed of three components of a phenol resin, a chromium(III) fluoride compound, and phosphoric acid is preferable.

[0105] The size of the metal terminal 2 may be appropriately set according to the size of the power storage device used and the like. The thickness of the metal terminal 2 is preferably about 50 to 1000 μm, more preferably about 70 to 800 μm. Also, the length of the metal terminal 2 is preferably about 1 to 200 mm, more preferably about 3 to 150 mm. Also, the width of the metal terminal 2 is preferably about 1 to 200 mm, more preferably about 3 to 150 mm.

[0106] [Exterior material 3 for power storage device] Examples of the exterior material 3 for a power storage device include those having a laminated structure composed 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. 8 shows an example of the cross-sectional structure of the exterior material 3 for a power storage device, in which a base material layer 31, an adhesive layer 32 provided as necessary, a barrier layer 33, an adhesive layer 34 provided as necessary, and a heat-sealable resin layer 35 are laminated in this order. In the exterior material 3 for a power storage device, the base material layer 31 is on the outer layer side and the heat-sealable resin layer 35 is on the innermost layer. When assembling the power storage device, the power storage device element 4 is sealed by bringing the heat-sealable resin layers 35 located at the peripheries of the power storage device elements 4 into contact with each other and heat-sealing them. Figs. 1 to 3 illustrate a power storage device 10 when using an embossed type exterior material 3 for a power storage device formed by embossing or the like, but the exterior material 3 for a power storage device may be a non-formed pouch type. Note that among pouch types, there are three-side seal, four-side seal, pillow type, etc., and any type may be used.

[0107] The thickness of the laminate constituting the exterior material 10 for a power storage device is not particularly limited. However, from the viewpoints of cost reduction, improvement of energy density, etc., for example, it is about 210 μm or less, preferably about 190 μm or less, about 180 μm or less, about 155 μm or less, about 120 μm or less. Also, from the viewpoint of maintaining the function of the exterior material for a power storage device of protecting the power storage device element, the thickness of the laminate constituting the exterior material 10 for a power storage device is preferably about 35 μm or more, about 45 μm or more, about 60 μm or more. Further, regarding the preferable range of the laminate constituting the exterior material 10 for a power storage device, for example, 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 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 210 μm, about 60 to 190 μm, about 60 to 180 μm, about 60 to 155 μm, about 60 to 120 μm can be mentioned. Particularly, when making the power storage device lightweight and thin-film, about 60 to 155 μm is preferable, and when improving the formability, about 155 to 190 μm is preferable.

[0108] (Base material layer 31) In the exterior material 3 for a power storage device, the base material layer 31 is a layer that functions as the base material of the exterior material for a power storage device and is the layer forming the outermost layer side.

[0109] The material for forming the base material layer 31 is not particularly limited as long as it has insulating properties. Examples of the material for forming the base material layer 31 include polyester, polyamide, epoxy, acrylic resin, fluororesin, polyurethane, silicone resin, phenol, polyetherimide, polyimide, and mixtures and copolymers thereof. Polyesters such as polyethylene terephthalate and polybutylene terephthalate are excellent in resistance to electrolytic solution and have the advantage that whitening and the like hardly occur due to the adhesion of the electrolytic solution, and are preferably used as the material for forming the base material layer 31. Also, the polyamide film is excellent in stretchability and can prevent the occurrence of whitening due to resin cracking of the base material layer 31 during molding, and is preferably used as the material for forming the base material layer 31.

[0110] The base material layer 31 may be formed of a resin film stretched uniaxially or biaxially, or may be formed of an unstretched resin film. Among these, a resin film stretched uniaxially or biaxially, particularly a resin film stretched biaxially, is preferably used as the base material layer 31 because its heat resistance is improved by orientation crystallization.

[0111] Among these, as the resin film forming the base material layer 31, nylon, polyester are preferable, and biaxially stretched nylon and biaxially stretched polyester are more preferable.

[0112] In order to improve the pinhole resistance and insulation properties when the base material layer 31 is used as a package for a power storage device, it is also possible to laminate resin films of different materials. Specifically, examples include a multilayer structure in which a polyester film and a nylon film are laminated, and a multilayer structure in which biaxially stretched polyester and biaxially stretched nylon are laminated. When the base material layer 31 has a multilayer structure, the resin films may be adhered via an adhesive, or may be directly laminated without an adhesive. When adhering without an adhesive, examples of the method include methods of adhering in a thermally melted state such as a coextrusion method, a sand laminate method, and a thermal laminate method.

[0113] Also, the base material layer 31 may be made to have a low friction coefficient in order to improve its formability. When the base material layer 31 is made to have a low friction coefficient, the friction coefficient of its surface is not particularly limited, but for example, 1.0 or less can be mentioned. To make the base material layer 31 have a low friction coefficient, examples include a mat treatment, formation of a thin film layer of a slip agent, and combinations thereof.

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

[0115] (Adhesive layer 32) In the exterior material 3 for the power storage device, the adhesive layer 32 is a layer disposed on the base material layer 31 as needed in order to impart adhesiveness to the base material layer 31. That is, the adhesive layer 32 is provided between the base material layer 31 and the barrier layer 33.

[0116] The adhesive layer 32 is formed of an adhesive capable of adhering the base material layer 31 and the barrier layer 33. The adhesive used for forming the adhesive layer 32 may be a two-component curable adhesive or a one-component curable adhesive. Also, the adhesion mechanism of the adhesive used for forming the adhesive layer 32 is not particularly limited, and it may be any of a chemical reaction type, a solvent volatilization type, a hot melt type, a hot press type, etc.

[0117] As the resin component of the adhesive that can be used for forming the adhesive layer 32, it has excellent spreadability, durability under high humidity conditions, yellowing suppression effect, heat deterioration suppression effect during heat sealing, etc., and from the viewpoint of suppressing the decrease in the laminate strength between the base material layer 31 and the barrier layer 33 and effectively suppressing the occurrence of delamination, preferably a two-component curable polyurethane-based adhesive; polyamide, polyester, or a blend resin of these and a modified polyolefin can be mentioned.

[0118] Also, the adhesive layer 32 may be multi-layered with different adhesive components. When the adhesive layer 32 is multi-layered with different adhesive components, from the viewpoint of improving the laminate strength between the base material layer 31 and the barrier layer 33, a resin excellent in adhesiveness to the base material layer 31 is selected as the adhesive component arranged on the base material layer 31 side, and an adhesive component excellent in adhesiveness to the barrier layer 33 is selected as the adhesive component arranged on the barrier layer 33 side. When the adhesive layer 32 is multi-layered with different adhesive components, specifically, as the adhesive component arranged on the barrier layer 33 side, preferably, acid-modified polyolefin, metal-modified polyolefin, a mixed resin of polyester and acid-modified polyolefin, a resin containing copolymerized polyester, etc. can be mentioned.

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

[0120] (Barrier layer 33) In the exterior material 3 for a power storage device, the barrier layer 33 is a layer that has a function of preventing water vapor, oxygen, light, etc. from entering the inside of the power storage device, in addition to improving the strength of the exterior material for the power storage device. The barrier layer 33 is preferably a metal layer, that is, a layer formed of a metal. Specifically, examples of the metal constituting the barrier layer 33 include aluminum, stainless steel, titanium, etc., and preferably aluminum. The barrier layer 33 can be formed by, for example, a metal foil, a metal vapor deposition film, an inorganic oxide vapor deposition film, a carbon-containing inorganic oxide vapor deposition film, a film provided with these vapor deposition films, etc., and is preferably formed by a metal foil, and more preferably formed by an aluminum foil. From the viewpoint of preventing wrinkles and pinholes from occurring in the barrier layer 33 during the manufacture of the exterior material for the power storage device, the barrier layer is, for example, soft aluminum foil such as annealed aluminum (JIS H4160:1994 A8021H-O, JIS H4160:1994 A8079H-O, JIS H4000:2014 A8021P-O, JIS H4000:2014 A8079P-O), etc., and is more preferably formed.

[0121] Regarding the thickness of the barrier layer 33, from the viewpoint of making the exterior material for the power storage device thinner and making it difficult for pinholes to occur during molding, it is preferably about 10 to 200 μm, more preferably about 20 to 100 μm, about 20 to 45 μm, about 45 to 65 μm, about 65 to 85 μm.

[0122] Also, the barrier layer 33 is preferably subjected to a chemical conversion treatment on at least one surface, preferably both surfaces, for the purpose of stabilizing adhesion, preventing dissolution and corrosion, etc. Here, the chemical conversion treatment refers to a treatment for forming a corrosion-resistant film on the surface of the barrier layer.

[0123] (Adhesive layer 34) In the exterior material 3 for a power storage device, the adhesive layer 34 is a layer provided between the barrier layer 33 and the heat-fusible resin layer 35 as necessary in order to firmly adhere the heat-fusible resin layer 35.

[0124] The subsequent layer 34 is formed of an adhesive capable of bonding the barrier layer 33 and the heat-sealable resin layer 35. The composition of the adhesive used for forming the adhesive layer is not particularly limited, and examples thereof include resin compositions containing acid-modified polyolefins. Examples of the acid-modified polyolefins can be the same as those exemplified in the first polyolefin layer 12a and the second polyolefin layer 12b.

[0125] Regarding the thickness of the adhesive layer 34, for example, it is about 1 to 40 μm, preferably about 2 to 30 μm.

[0126] (Heat-sealable resin layer 35) In the exterior material 3 for the power storage device, the heat-sealable resin layer 35 corresponds to the innermost layer and is a layer in which the heat-sealable resin layers are heat-sealed to seal the power storage device element during the assembly of the power storage device.

[0127] The resin component used for the heat-sealable resin layer 35 is not particularly limited as long as it can be heat-sealed, and examples thereof include polyolefins and cyclic polyolefins.

[0128] Specific examples of the polyolefin include polyethylene such as low-density polyethylene, medium-density polyethylene, high-density polyethylene, and linear low-density polyethylene; crystalline or amorphous polypropylene such as homopolypropylene, block copolymers of polypropylene (for example, block copolymers of propylene and ethylene), and random copolymers of polypropylene (for example, random copolymers of propylene and ethylene); and terpolymers of ethylene-butene-propylene. Among these polyolefins, polyethylene and polypropylene are preferably mentioned.

[0129] The cyclic polyolefin is a copolymer of an olefin and a cyclic monomer. Examples of the olefin that is a constituent monomer of the cyclic polyolefin include ethylene, propylene, 4-methyl-1-pentene, butadiene, isoprene, and the like. Further, examples of the cyclic monomer that is a constituent monomer of the cyclic polyolefin include cyclic alkenes such as norbornene; specifically, cyclic dienes such as cyclopentadiene, dicyclopentadiene, cyclohexadiene, norbornadiene, and the like. Among these polyolefins, cyclic alkenes are preferable, and norbornene is more preferable. Styrene is also included as a constituent monomer.

[0130] Among these resin components, preferably crystalline or amorphous polyolefins, cyclic polyolefins, and blend polymers thereof; more preferably polyethylene, polypropylene, a copolymer of ethylene and norbornene, and blend polymers of two or more of these are included.

[0131] The heat-sealable resin layer 35 may be formed of a single resin component alone, or may be formed of a blend polymer combining two or more resin components. Further, the heat-sealable resin layer 35 may be formed of only one layer, but may be formed of two or more layers with the same or different resin components. It is particularly preferable that the resins of the second polyolefin layer 12b and the heat-sealable resin layer 35 are common, as the adhesion between these layers is improved.

[0132] Further, the thickness of the heat-sealable resin layer 35 is not particularly limited, but may be about 2 to 2000 μm, preferably about 5 to 1000 μm, more preferably about 10 to 500 μm. Also, examples of the thickness of the heat-sealable resin layer 35 include about 100 μm or less, preferably about 85 μm or less, and more preferably about 15 to 85 μm. For example, when the thickness of the aforementioned adhesive layer 34 is 10 μm or more, the thickness of the heat-sealable resin layer 35 is preferably about 85 μm or less, more preferably about 15 to 45 μm. For example, when the thickness of the aforementioned adhesive layer 34 is less than 10 μm or when the adhesive layer 34 is not provided, the thickness of the heat-sealable resin layer 35 is preferably about 20 μm or more, more preferably about 35 to 85 μm.

[0133] From the viewpoint of more suitably exhibiting the effects of the present disclosure, the Martens hardness of the heat-sealable resin layer 35 is preferably about 35 N / mm 2 or less, more preferably about 30 N / mm 2 or less, even more preferably about 25 N / mm 2 or less, and also preferably about 10 N / mm 2 or more, more preferably about 15 N / mm 2 or more, even more preferably about 18 N / mm 2 or more, and even more preferably about 20 N / mm 2 or more, and the preferable range is about 10 to 35 N / mm 2 or so, about 10 to 30 N / mm 2 or so, about 10 to 25 N / mm 2 or so, about 15 to 35 N / mm 2 or so, 15 ~30 N / mm 2 or so, about 15 to 25 N / mm 2 or so, about 18 to 35 N / mm 2 or so, about 18 to 3 0 N / mm 2 or so, about 18 to 25 N / mm 2 or so, about 20 to 35 N / mm 2 or so, about 20 to 30 N / mm 2 or so, about 20 to 25 N / mm 2 or so can be mentioned.

[0134] The exterior material for a power storage device of the present disclosure can also be in the form of a kit including an exterior material for a power storage device for use in a power storage device and the adhesive film for a metal terminal of the present disclosure. Also in this case, the power storage device to be applied includes at least a power storage device element having a positive electrode, a negative electrode, and an electrolyte, an exterior material for a power storage device that seals the power storage device element, and metal terminals that are electrically connected to the positive electrode and the negative electrode, respectively, and protrude outside the exterior material for a power storage device. The kit of the present disclosure is used such that the adhesive film for a metal terminal of the present disclosure is interposed between the metal terminal and the exterior material for a power storage device during use.

[0135] 2. Energy Storage Device The power storage device 10 of the present disclosure includes at least a power storage device element 4 having a positive electrode, a negative electrode, and an electrolyte, an exterior material 3 for a power storage device that seals the power storage device element 4, and metal terminals 2 that are electrically connected to the positive electrode and the negative electrode, respectively, and protrude outside the exterior material 3 for a power storage device. In the power storage device 10 of the present disclosure, the adhesive film 1 for a metal terminal of the present disclosure is interposed between the metal terminal 2 and the exterior material 3 for a power storage device. That is, the power storage device 10 of the present disclosure can be manufactured by a method including a step of interposing the adhesive film 1 for a metal terminal of the present disclosure between the metal terminal 2 and the exterior material 3 for a power storage device.

[0136] Specifically, a power storage device element 4 including at least a positive electrode, a negative electrode, and an electrolyte is covered with an exterior material 3 for a power storage device, with metal terminals 2 connected to each of the positive electrode and the negative electrode protruding outward. The adhesive film 1 for a metal terminal of the present disclosure is interposed between the metal terminal 2 and a heat-sealable resin layer 35, and the flange portion of the exterior material 3 for a power storage device (a region where the heat-sealable resin layers 35 contact each other, and the peripheral portion 3a of the exterior material 3 for a power storage device) is formed around the power storage device element 4 so as to be covered, and the heat-sealable resin layers 35 of the flange portion are heat-sealed and sealed, thereby providing a power storage device 10 using the exterior material 3 for a power storage device. When the power storage device element 4 is accommodated using the exterior material 3 for a power storage device, the heat-sealable resin layer 35 of the exterior material 3 for a power storage device is used so as to be on the inner side (the surface in contact with the power storage device element 4).

[0137] The exterior material for a power storage device of the present disclosure can be suitably used for power storage devices such as batteries (including capacitors, capacitors, etc.). Further, the exterior material for a power storage device of the present disclosure can be used for either a primary battery or a secondary battery, but is preferably a secondary battery. The type of secondary battery to which the exterior material for a power storage device of the present disclosure is applied is not particularly limited, and examples include lithium ion batteries, lithium ion polymer batteries, all-solid-state batteries, semi-solid-state batteries, quasi-solid-state batteries, polymer batteries, all-resin batteries, lead-acid batteries, nickel-hydrogen storage batteries, nickel-cadmium storage batteries, nickel-iron storage batteries, nickel-zinc storage batteries, silver oxide-zinc storage batteries, metal-air batteries, polyvalent cation batteries, capacitors, capacitors, and the like. Among these secondary batteries, lithium ion batteries and lithium ion polymer batteries are mentioned as suitable application targets for the exterior material for a power storage device of the present disclosure.

Examples

[0138] Examples and comparative examples are shown below to explain the present disclosure in detail. However, the present disclosure is not limited to the examples.

[0139] <Manufacture of Adhesive Film for Metal Terminal> Example 1 Using an extruder and a T-die casting device, on one side of a polypropylene film (CPP layer (unstretched homopolypropylene layer A), thickness 80 μm) as a base material, polypropylene (r-PP layer (random polypropylene layer X), thickness 60 μm) is used as the first polyolefin layer on the exterior material side. On the other side, maleic anhydride-modified polypropylene containing carbon black as a black coloring layer (r-PPa layer (maleic anhydride-modified random polypropylene layer L), thickness 60 μm) is extruded as the second polyolefin layer on the metal terminal side, and an adhesive film for metal terminals (total thickness 200 μm) with the first polyolefin layer (r-PP layer, thickness 60 μm) / base material (CPP layer, thickness 80 μm) / second polyolefin layer (r-PPa layer, thickness 60 μm) laminated in order is obtained. The martensitic hardness and tensile elastic modulus are adjusted by adjusting the cooling conditions of the selected resin and the film-forming resin so as to obtain the desired physical properties. The cooling condition at this time (the time until the resin extruded from the T-die reaches room temperature) is set as X seconds and used as the reference time for Examples 2-7 and Comparative Examples 1-3 described later. The tensile elastic modulus of the obtained adhesive film for metal terminals, base material, first polyolefin layer, and second polyolefin layer, and the martensitic hardness of each layer are as described in Table 1, respectively.

[0140] Example 2 Using an extruder and a T-die casting device, on one side of a polypropylene film (CPP layer (unstretched homopolypropylene layer A), thickness 60 μm) as a base material, polypropylene (r-PP layer (random polypropylene layer Z), thickness 80 μm), on the other hand, maleic anhydride-modified polypropylene containing carbon black as a black colored layer as the second polyolefin layer on the metal terminal side (r-PPa layer (maleic anhydride-modified random polypropylene layer L), thickness 60 μm) was extruded, and the first polyolefin layer (r-PP layer, thickness 60 μm) / substrate (CPP layer, thickness 80 μm) / second polyolefin layer (r-PPa layer, thickness 60 μm) were laminated in order to obtain an adhesive film for metal terminals (total thickness 200 μm). The martensitic hardness and tensile modulus were adjusted by adjusting the resin to be selected and the cooling conditions of the film-forming resin so as to obtain the desired physical properties. The cooling conditions were set to 4 / 3X seconds. The tensile modulus of the obtained adhesive film for metal terminals, the substrate, the first polyolefin layer, and the second polyolefin layer, and the martensitic hardness of each layer are as described in Table 1, respectively.

[0141] Example 3 Using an extruder and a T-die casting device, on one side of a polypropylene film (CPP layer (unoriented homopolypropylene layer A), thickness 80 μm) as a substrate, polypropylene (r-PP layer (random polypropylene layer X), thickness 60 μm), on the other hand, maleic anhydride-modified polypropylene containing carbon black as a black colored layer as the second polyolefin layer on the metal terminal side (r-PPa layer (maleic anhydride-modified random polypropylene layer M), thickness 60 μm) was extruded, and the first polyolefin layer (r-PP layer, thickness 60 μm) / substrate (CPP layer, thickness 80 μm) / second polyolefin layer (r-PPa layer, thickness 60 μm) were laminated in order to obtain an adhesive film for metal terminals (total thickness 200 μm). The martensitic hardness and tensile modulus were adjusted by adjusting the resin to be selected and the cooling conditions of the film-forming resin so as to obtain the desired physical properties. As the cooling condition, the time until the resin extruded from the T-die reached room temperature was set to X seconds. The tensile modulus of the obtained adhesive film for metal terminals, the substrate, the first polyolefin layer, and the second polyolefin layer, and the martensitic hardness of each layer are as described in Table 1, respectively.

[0142] Example 4 Using an extruder and a T-die casting device, on one side of a polypropylene film (CPP layer (unoriented homopolypropylene layer A, thickness 80 μm)) as a base material, polypropylene (r-PP layer (random polypropylene layer Y), thickness 60 μm) is used as the first polyolefin layer on the exterior material side, and on the other side, maleic anhydride-modified polypropylene containing carbon black as a black coloring layer (r-PPa layer (maleic anhydride-modified random polypropylene layer L), thickness 60 μm) is used as the second polyolefin layer on the metal terminal side. The first polyolefin layer (r-PP layer, thickness 60 μm) / base material (CPP layer, thickness 80 μm) / second polyolefin layer (r-PPa layer, thickness 60 μm) are laminated in order to obtain an adhesive film for metal terminals (total thickness 200 μm). The martensitic hardness and tensile modulus were adjusted by adjusting the cooling conditions of the selected resin and the film-forming resin so as to obtain the desired physical properties. The cooling condition was X seconds. The tensile modulus of the obtained adhesive film for metal terminals, the base material, the first polyolefin layer, and the second polyolefin layer, as well as the martensitic hardness of each layer, are as described in Table 1 respectively.

[0143] Example 5 Using an extruder and a T-die casting device, on one side of a polypropylene film (CPP layer (unoriented homopolypropylene layer B), thickness 80 μm)) as a base material, polypropylene (r-PP layer (random polypropylene layer Y), thickness 60 μm), on the other hand, maleic anhydride-modified polypropylene containing carbon black as a black colored layer as the second polyolefin layer on the metal terminal side (r-PPa layer (maleic anhydride-modified random polypropylene layer L), thickness 60 μm) was extruded, and the first polyolefin layer (r-PP layer, thickness 60 μm) / substrate (CPP layer, thickness 80 μm) / second polyolefin layer (r-PPa layer, thickness 60 μm) were sequentially laminated to obtain an adhesive film for metal terminals (total thickness 200 μm). The martensitic hardness and tensile modulus were adjusted by adjusting the resin to be selected and the cooling conditions of the film-forming resin so as to obtain the desired physical properties. The cooling conditions were set as X seconds. The tensile modulus of the obtained adhesive film for metal terminals, substrate, first polyolefin layer, and second polyolefin layer, and the martensitic hardness of each layer are as shown in Table 1, respectively.

[0144] Example 6 Using an extruder and a T-die casting device, on one side of a polypropylene film (CPP layer (unoriented homopolypropylene layer C, thickness 65 μm)) as a substrate, polypropylene (r-PP layer (random polypropylene layer W, thickness 60 μm)) as the first polyolefin layer on the exterior material side, and on the other hand, maleic anhydride-modified polypropylene (r-PPa layer (maleic anhydride-modified random polypropylene layer N), thickness 75 μm) as the second polyolefin layer on the metal terminal side were extruded, and the first polyolefin layer (r-PP layer, thickness 60 μm) / substrate (CPP layer, thickness 80 μm) / second polyolefin layer (r-PPa layer, thickness 60 μm) were sequentially laminated to obtain an adhesive film for metal terminals (total thickness 200 μm). The martensitic hardness and tensile modulus were adjusted by adjusting the resin to be selected and the cooling conditions of the film-forming resin so as to obtain the desired physical properties. The cooling conditions were set as 1 / 4X seconds. The tensile modulus of the obtained adhesive film for metal terminals, substrate, first polyolefin layer, and second polyolefin layer, and the martensitic hardness of each layer are as shown in Table 1, respectively.

[0145] Example 7 Using an extruder and a T-die casting device, on one side of a polypropylene film (CPP layer (unoriented homopolypropylene layer A), thickness 80 μm) as a base material, polypropylene (r-PP layer (random polypropylene layer Y), thickness 60 μm) is used as the first polyolefin layer on the exterior material side. On the other side, maleic anhydride-modified polypropylene containing carbon black (r-PPa layer (maleic anhydride-modified random polypropylene layer L), thickness 20 μm) is used as a black colored layer, and maleic anhydride-modified polypropylene (r-PPa layer (maleic anhydride-modified random polypropylene layer L), thickness 40 μm) is extruded as the second polyolefin layer on the metal terminal side, obtaining an adhesive film for metal terminals (total thickness 200 μm) with the first polyolefin layer (r-PP layer, thickness 60 μm) / base material (CPP layer, thickness 80 μm) / colored layer (r-PPa layer, thickness 20 μm) / second polyolefin layer (r-PPa layer, thickness 40 μm) laminated in sequence. The ratio of the thickness of the colored layer to the thickness of the adhesive film for metal terminals was set to 0.1. The martensitic hardness and tensile modulus were adjusted by adjusting the cooling conditions of the selected resin and the film-forming resin so as to obtain the target physical properties. The cooling condition was set to X seconds. The tensile moduli of the obtained adhesive film for metal terminals, base material, first polyolefin layer, and second polyolefin layer, and the martensitic hardness of each layer are as described in Table 1, respectively.

[0146] Comparative Example 1 Using an extruder and a T-die casting device, on one side of a polypropylene film (CPP layer (unstretched homopolypropylene layer D, thickness 80 μm)) as a base material, polypropylene (r-PP layer (random polypropylene layer X), thickness 60 μm) is used as the first polyolefin layer on the exterior material side, and on the other side, maleic anhydride-modified polypropylene containing carbon black as a black colored layer (r-PPa layer (maleic anhydride-modified random polypropylene layer L), thickness 60 μm) is used as the second polyolefin layer on the metal terminal side. Extrusion is carried out to obtain an adhesive film for metal terminals (total thickness 200 μm) in which the first polyolefin layer (r-PP layer, thickness 60 μm) / base material (CPP layer, thickness 80 μm) / second polyolefin layer (r-PPa layer, thickness 60 μm) are laminated in order. The martensitic hardness and tensile modulus were adjusted by adjusting the resin to be selected and the cooling conditions of the film-forming resin so as to obtain the desired physical properties. As the cooling condition, the time until the resin extruded from the T-die reaches room temperature was set to 1 / 2X seconds. The tensile modulus of the obtained adhesive film for metal terminals, base material, first polyolefin layer, and second polyolefin layer, and the martensitic hardness of each layer are as described in Table 1 respectively.

[0147] Comparative Example 2 Using an extruder and a T-die casting device, on one side of a polypropylene film (CPP layer (unstretched homopolypropylene layer D)) as a base material, polypropylene (r-PP layer (random polypropylene layer V), thickness 60 μm). On the other hand, maleic anhydride modified polypropylene containing carbon black as a black colored layer was extruded as the second polyolefin layer on the metal terminal side (r-PPa layer (maleic anhydride modified random polypropylene layer L), and an adhesive film for metal terminals with the first polyolefin layer (r-PP layer, thickness 60 μm) / substrate (CPP layer, thickness 80 μm) / second polyolefin layer (r-PPa layer, thickness 60 μm) laminated in order was obtained (total thickness 200 μm). The martensitic hardness and tensile modulus were adjusted by adjusting the cooling conditions of the selected resin and the film-forming resin so as to obtain the desired physical properties. As the cooling condition, the time until the resin extruded from the T-die reached room temperature was set to 1 / 2X seconds. The tensile modulus of the obtained adhesive film for metal terminals, the substrate, the first polyolefin layer, and the second polyolefin layer, and the martensitic hardness of each layer are as described in Table 1, respectively.

[0148] Comparative Example 3 Using an extruder and a T-die casting device, on one side of a polypropylene film (CPP layer (unstretched homopolypropylene layer E), thickness 80 μm) as a substrate, polypropylene was used as the first polyolefin layer on the exterior material side (r-PP layer (random polypropylene layer Y), thickness 60 μm). On the other hand, maleic anhydride modified polypropylene containing carbon black as a black colored layer was extruded as the second polyolefin layer on the metal terminal side (r-PPa layer (maleic anhydride modified random polypropylene layer L), thickness 60 μm), and an adhesive film for metal terminals with the first polyolefin layer (r-PP layer, thickness 60 μm) / substrate (CPP layer, thickness 80 μm) / second polyolefin layer (r-PPa layer, thickness 60 μm) laminated in order was obtained (total thickness 200 μm). The martensitic hardness and tensile modulus were adjusted by adjusting the cooling conditions of the selected resin and the film-forming resin so as to obtain the desired physical properties. As the cooling condition, the time until the resin extruded from the T-die reached room temperature was set to 1 / 2X seconds. The tensile modulus of the obtained adhesive film for metal terminals, the substrate, the first polyolefin layer, and the second polyolefin layer, and the martensitic hardness of each layer are as described in Table 1, respectively.

[0149] <Tensile modulus of elasticity> The method for measuring the tensile modulus of elasticity of the adhesive film, the substrate, the colored layer, the first polyolefin layer, and the second polyolefin layer is as follows. For the tensile modulus of elasticity of the substrate, the colored layer, the first polyolefin layer, and the second polyolefin layer, each layer was prepared as a single layer and used as a measurement target sample. These single layers were prepared by forming a film on a polyethylene terephthalate film and peeling it off. In accordance with the provisions of JIS K7161-1 (ISO527-1), the tensile modulus of elasticity of the sample in a 25°C environment was measured. Specifically, the sample was cut into a strip shape with a width (TD) of 15 mm and a length (MD) of 50 mm. Next, in a 25°C environment, using a tensilon universal material testing machine (RTG-1210 manufactured by A&D Company), the stress-strain curve of the test piece of the sample was obtained under the conditions of a tensile speed of 300 mm / min and a chuck distance of 30 mm, and the tensile modulus of elasticity of each sample was determined from the slope of the straight line connecting two points of strain of 0.05% and 0.25%. The results are shown in Table 1.

[0150] <Martens hardness> The method for measuring the Martens hardness of the base material, the colored layer, the first polyolefin layer, and the second polyolefin layer is as follows. Regarding the Martens hardness of the base material, the colored layer, the first polyolefin layer, and the second polyolefin layer, respectively, using the adhesive film for metal terminals as a sample, each layer in the state laminated on the sample was set as the measurement target. Specifically, as a pretreatment of the sample to be measured, the adhesive film for metal terminals was cut into a length of 30 mm and a width of 15 mm. Next, the sample was embedded in an epoxy cold embedding resin and dried for about 1 day. Then, using a Tegrapol-35 mechanical polishing device manufactured by Maruto Struers Co., Ltd., polishing was performed in the direction parallel to the TD direction to make the cross-section of the sample have a surface roughness of about 1.0 μm. As the measurement by the indentation method, it was carried out using a Pico-Denter HM-500 manufactured by Fisher Instruments, and the measurement was performed in a direction perpendicular to the cross-section (the central part in the thickness direction) in the thickness direction of the layer to be measured. The measurement conditions are as follows. Regarding the Martens hardness of the heat-sealing resin layer of the exterior material for the power storage device described later, the exterior material for the power storage device was used as a sample, and the heat-sealing resin layer in the state laminated on the sample was measured in the same manner. The results are shown in Table 1.

[0151] [Measurement Conditions for Martens Hardness] The load is 25 mN. The load application acceleration is 25 mN / 20 seconds. The holding time is 5 seconds. The load unloading speed is 25 mN / 20 seconds. The indenter is a Vickers indenter with a face angle of 136° at the tip of a regular square pyramid. The measurement temperature is 25 °C. The measured value is the average value of a total of 8 measured values obtained by changing the measurement location 10 times and excluding one maximum value and one minimum value.

[0152] <Measurement of the Seal Strength (Adhesive Strength) between the Adhesive Film and the Exterior Material> The seal strength (adhesive strength) between the exterior material of the adhesive film and the metal terminal was measured by the following procedure. The results are shown in Table 1.

[0153] (Fabrication of the Exterior Material) First, an exterior material for a power storage device (hereinafter sometimes simply referred to as "exterior material") was produced by the following procedure. A base material layer (30 μm thick) composed of a polyethylene terephthalate film (12 μm thick) / adhesive layer (3 μm thick) / nylon film (15 μm thick) was laminated on an aluminum alloy foil (40 μm thick) by a dry lamination method, and a heat-sealing resin layer was laminated on the other side by coextrusion. Specifically, a two-component urethane adhesive (polyol compound and aromatic isocyanate compound) was applied on the nylon film to form an adhesive layer (3 μm thick) on the nylon film. Next, the adhesive layer and the polyethylene terephthalate film were laminated on the nylon film to produce a base material layer. Next, a two-component urethane adhesive (polyol compound and aromatic isocyanate compound) was applied on one side of a barrier layer made of an aluminum alloy foil to form an adhesive layer (3 μm thick) on the aluminum alloy foil. Next, after laminating the adhesive layer and the base material layer with the nylon film side as the adhesive surface on the aluminum alloy foil, an aging treatment was carried out to produce a laminate of the base material layer / adhesive layer / barrier layer. Next, an adhesive layer (40 μm thick, arranged on the metal layer side) made of maleic anhydride-modified polypropylene resin and a heat-sealing resin layer (40 μm thick, innermost layer) made of random polypropylene resin were coextruded on the barrier layer of the laminate to laminate the adhesive layer / heat-sealing resin layer on the barrier layer, and an exterior material for a power storage device in which the base material layer, adhesive layer, barrier layer, adhesive layer, and heat-sealing resin layer were laminated in this order was obtained. The Martens hardness of the heat-sealing resin layer of the obtained exterior material was 19.5 N / mm 2 as shown in Table 1

[0154] Next, as the metal terminal 2, an aluminum foil (JIS H4160:1994 A8079H-O) with MD of 25 mm, TD of 22.5 mm, and a thickness of 400 μm was prepared. Also, each adhesive film 1 obtained in the examples and comparative examples was cut to MD of 25 mm and TD of 20 mm. Next, as shown in the schematic diagram of FIG. 9, a metal terminal was sandwiched between two adhesive films to obtain a laminate of adhesive film / metal terminal / adhesive film. At this time, the MD and TD of the metal terminal were made to coincide with the MD and TD of the adhesive film, respectively, and the laminate was formed such that the centers of the metal terminal and the adhesive film coincided (see FIG. 9(a)). Also, the second polyolefin layer of the adhesive film for the metal terminal was arranged on the metal terminal side. Next, with the laminate sandwiched between two polytetrafluoroethylene films (PTFE films, thickness 100 μm), heating was performed under the conditions of a temperature of 200°C, a surface pressure of 0.25 MPa, and for 16 seconds to thermally fuse the adhesive film to the metal terminal to produce a metal terminal with an adhesive film attached (see FIG. 9(b)). Next, the exterior material 3 was cut into a size of TD 30 mm and MD 100 mm. As shown in the schematic diagram of FIG. 10, they were opposed to each other with the heat-sealing resin layer of the exterior material on the inner side, and the obtained laminate was sandwiched between the opposed heat-sealing resin layers (see FIG. 10(a)). At this time, the MD and TD of the exterior material were laminated so as to coincide with the width direction and the length direction of the laminate, respectively. In this state, using a heat-sealing tester, heat-sealing (see the hatched area S in FIG. 10(b)) was performed under the conditions of a width of 5 mm (5 mm in the y-axis direction in FIG. 10(b)), 215°C, a surface pressure of 3.0 MPa, and 1.6 seconds, and then naturally cooled to 25°C to obtain a laminate in which the exterior material and the adhesive film were heat-sealed together (see FIG. 10(b)). Next, the central part in the short-side direction of the obtained laminate was cut to a width of 15 mm (the cutting position is shown by the two-dot chain line in FIG. 10(b)). Next, in an environment of 25°C, the adhesive film and the heat-sealing resin layer of the exterior material were peeled off using a tensilon universal material testing machine (RTG-1210 manufactured by A&D Company). At this time, the metal terminal with the adhesive film and the exterior material were chucked respectively to peel the adhesive film and the heat-sealing resin layer of the exterior material. The maximum strength at the time of peeling was defined as the peeling strength (N / 15 mm) with respect to the exterior material. The peeling speed was 5 mm / min, the peeling angle was 180°, the distance between chucks was 30 mm, and the average value of three measurements was taken.

[0155]

Table 1

[0156] As described above, the present disclosure provides an invention in the following aspects. Item 1. An adhesive film for a metal terminal interposed between a metal terminal electrically connected to an electrode of a power storage device element and an exterior material for a power storage device that seals the power storage device element, The adhesive film for a metal terminal is composed of a laminate including at least a first polyolefin layer disposed on the surface on the exterior material side for the power storage device, a base material, and a second polyolefin layer disposed on the metal terminal side, in this order. The tensile elastic modulus of the adhesive film for a metal terminal is 700 MPa or less. The base material is the layer located between the first polyolefin layer and the second polyolefin layer, and has the highest Martens hardness measured in a direction perpendicular to the cross-section in the thickness direction of the layer. The absolute value of the difference between the Martens hardness measured in a direction perpendicular to the cross-section in the thickness direction of the base material and the Martens hardness measured in a direction perpendicular to the cross-section in the thickness direction of the first polyolefin layer is 10 N / mm 2 An adhesive film for metal terminals as described below. Item 2. The adhesive film for metal terminals according to Item 1, wherein the absolute value of the difference between the tensile elastic modulus of the base material and the tensile elastic modulus of the first polyolefin layer is 400 MPa or less. Item 3. The adhesive film for metal terminals according to Item 1 or 2, wherein the value of the tensile elastic modulus of the second polyolefin layer is less than or equal to the value of the tensile elastic modulus of the base material. Item 4. The absolute value of the difference between the tensile elastic modulus of the first polyolefin layer and the tensile elastic modulus of the base material is 300 MPa or less, the absolute value of the difference between the tensile elastic modulus of the second polyolefin layer and the tensile elastic modulus of the base material is 300 MPa or less, The adhesive film for metal terminals according to any one of Items 1 to 3, wherein the absolute value of the difference between the tensile elastic modulus of the first polyolefin layer and the tensile elastic modulus of the second polyolefin layer is 300 MPa or less. Item 5. The adhesive film for metal terminals according to any one of Items 1 to 4, comprising a colored layer between the first polyolefin layer and the second polyolefin layer. Item 6. The adhesive film for metal terminals according to any one of Items 1 to 5, comprising a colored layer between the second polyolefin layer and the base material. Item 7. A colored layer is provided between the first polyolefin layer and the second polyolefin layer, and the difference between the Martens hardness of the base material and the Martens hardness of the colored layer is 10 N / mm 2 as follows. The adhesive film for metal terminals according to any one of Items 1 to 6. Item 8. A colored layer is provided between the first polyolefin layer and the second polyolefin layer. The adhesive film for metal terminals according to any one of Items 1 to 7, wherein the colored layer is black, gray, or white. Item 9. A colored layer is provided between the first polyolefin layer and the second polyolefin layer. The adhesive film for metal terminals according to any one of Items 1 to 8, wherein the ratio of the thickness of the colored layer to the thickness of the adhesive film for metal terminals is 0.30 or less. Item 10. A colored layer is provided between the first polyolefin layer and the second polyolefin layer. The adhesive film for metal terminals according to any one of Items 1 to 9, wherein the thickness of the colored layer is 50 μm or less. Item 11. The exterior material for a power storage device is composed of a laminate including at least a base material layer, a barrier layer, and a heat-sealable resin layer in this order. The adhesive film for metal terminals according to any one of Items 1 to 10, wherein the Martens hardness of the heat-sealable resin layer is 35 N / mm 2 or less. The adhesive film for metal terminals according to any one of Items 1 to 10. Item 12. A method for manufacturing an adhesive film for metal terminals, which is interposed between a metal terminal electrically connected to an electrode of a power storage device element and an exterior material for a power storage device that seals the power storage device element. The adhesive film for metal terminals is composed of a laminate including at least a first polyolefin layer disposed on the surface on the exterior material side of the power storage device, a base material, and a second polyolefin layer disposed on the metal terminal side in this order. The tensile elastic modulus of the adhesive film for metal terminals is 700 MPa or less. The base material is the layer having the largest Martens hardness measured in a direction perpendicular to the cross-section in the thickness direction of the layer among the layers located between the first polyolefin layer and the second polyolefin layer. The absolute value of the difference between the Martens hardness measured in a direction perpendicular to the cross-section in the thickness direction of the base material and the Martens hardness measured in a direction perpendicular to the cross-section in the thickness direction of the first polyolefin layer is 10 N / mm2 The manufacturing method of the adhesive film for metal terminals as follows. Item 13. A metal terminal with an adhesive film for metal terminals, wherein the adhesive film for metal terminals according to any one of Items 1 to 11 is attached to the metal terminal. Item 14. A power storage device comprising at least a power storage device element having a positive electrode, a negative electrode, and an electrolyte, an exterior material for the power storage device for sealing the power storage device element, and metal terminals electrically connected to each of the positive electrode and the negative electrode and protruding outside the exterior material for the power storage device, A power storage device, wherein the adhesive film for metal terminals according to any one of Items 1 to 11 is interposed between the metal terminal and the exterior material for the power storage device. Item 15. A manufacturing method of a power storage device comprising at least a power storage device element having a positive electrode, a negative electrode, and an electrolyte, an exterior material for the power storage device for sealing the power storage device element, and metal terminals electrically connected to each of the positive electrode and the negative electrode and protruding outside the exterior material for the power storage device, A manufacturing method of a power storage device, comprising a step of interposing the adhesive film for metal terminals according to any one of Items 1 to 11 between the metal terminal and the exterior material for the power storage device and sealing the power storage device element with the exterior material for the power storage device. Item 16. An exterior material for a power storage device for use in a power storage device, The power storage device comprises at least a power storage device element having a positive electrode, a negative electrode, and an electrolyte, the exterior material for the power storage device for sealing the power storage device element, and metal terminals electrically connected to each of the positive electrode and the negative electrode and protruding outside the exterior material for the power storage device, and an adhesive film for metal terminals is interposed between the metal terminal and the exterior material for the power storage device, The adhesive film for metal terminals is the adhesive film for metal terminals according to any one of Items 1 to 11, The exterior material for the power storage device is composed of a laminate comprising at least a base material layer, a barrier layer, and a heat-sealable resin layer. Item 17. A kit comprising an exterior material for a power storage device for use in a power storage device and the adhesive film for metal terminals according to any one of Items 1 to 11, wherein the power storage device includes at least a power storage device element including a positive electrode, a negative electrode, and an electrolyte, the exterior material for the power storage device that seals the power storage device element, and metal terminals that are electrically connected to each of the positive electrode and the negative electrode and protrude outside the exterior material for the power storage device, and the kit is used such that the adhesive film for metal terminals is interposed between the metal terminals and the exterior material for the power storage device during use.

Explanation of Signs

[0157] 1 Adhesive film for metal terminals 2 Metal terminals 3 Exterior material for power storage device 3a Peripheral portion of the exterior material for power storage device 4 Power storage device element 10 Power storage device 11 Base material 12a First polyolefin layer 12b Second polyolefin layer 12c Third layer (resin layer) 12d Fourth layer (resin layer) 14 Coloring layer 31 Base material layer 32 Adhesive layer 33 Barrier layer 34 Adhesive layer 35 Heat-fusible resin layer

Claims

1. An adhesive film for a metal terminal interposed between a metal terminal electrically connected to an electrode of a power storage device element and an exterior material for a power storage device that seals the power storage device element, wherein the adhesive film for a metal terminal is composed of a laminate including, in this order, a first polyolefin layer disposed on at least the surface on the exterior material side for the power storage device, a base material, and a second polyolefin layer disposed on the metal terminal side, the tensile elastic modulus of the adhesive film for a metal terminal is 700 MPa or less, the base material is the layer among the layers located between the first polyolefin layer and the second polyolefin layer that has the greatest Martens hardness measured in a direction perpendicular to the cross-section in the thickness direction of the layer, The absolute value of the difference between the Martens hardness measured in a direction perpendicular to the cross-section in the thickness direction of the base material and the Martens hardness measured in a direction perpendicular to the cross-section in the thickness direction of the first polyolefin layer is 10 N / mm 2 is as follows, an adhesive film for a metal terminal, comprising a colored layer between the second polyolefin layer and the base material.

2. The adhesive film for a metal terminal according to claim 1, wherein the absolute value of the difference between the tensile elastic modulus of the base material and the tensile elastic modulus of the first polyolefin layer is 400 MPa or less.

3. The adhesive film for a metal terminal according to claim 1 or 2, wherein the value of the tensile elastic modulus of the second polyolefin layer is less than or equal to the value of the tensile elastic modulus of the base material.

4. The absolute value of the difference between the tensile elastic modulus of the first polyolefin layer and the tensile elastic modulus of the base material is 300 MPa or less, the absolute value of the difference between the tensile elastic modulus of the second polyolefin layer and the tensile elastic modulus of the base material is 300 MPa or less, The adhesive film for a metal terminal according to claim 1 or 2, wherein the absolute value of the difference between the tensile elastic modulus of the first polyolefin layer and the tensile elastic modulus of the second polyolefin layer is 300 MPa or less.

5. The adhesive film for a metal terminal according to claim 1 or 2, comprising a colored layer between the first polyolefin layer and the second polyolefin layer.

6. Comprising a colored layer between the first polyolefin layer and the second polyolefin layer, The difference between the martensite hardness of the base material and the martensite hardness of the colored layer is 10 N / mm 2 The adhesive film for metal terminals according to claim 1 or 2, wherein the difference is 10 N / mm or less.

7. Comprising a colored layer between the first polyolefin layer and the second polyolefin layer, The adhesive film for a metal terminal according to claim 1 or 2, wherein the colored layer is black, gray, or white.

8. Comprising a colored layer between the first polyolefin layer and the second polyolefin layer, The adhesive film for metal terminals according to claim 1 or 2, wherein the ratio of the thickness of the colored layer to the thickness of the adhesive film for metal terminals is 0.30 or less.

9. A colored layer is provided between the first polyolefin layer and the second polyolefin layer, The adhesive film for metal terminals according to claim 1 or 2, wherein the thickness of the colored layer is 50 μm or less.

10. The exterior material for the power storage device is composed of a laminate including at least a base material layer, a barrier layer, and a heat-sealable resin layer in this order. The Martens hardness of the heat-fusible resin layer is 35 N / mm 2 The adhesive film for metal terminals according to claim 1 or 2, wherein the Martens hardness is 35 N / mm or less.

11. A method for manufacturing an adhesive film for metal terminals, which is interposed between a metal terminal electrically connected to an electrode of a power storage device element and an exterior material for a power storage device that seals the power storage device element, The adhesive film for metal terminals is composed of a laminate including at least a first polyolefin layer disposed on the surface on the side of the exterior material for the power storage device, a base material, and a second polyolefin layer disposed on the side of the metal terminal in this order. The tensile elastic modulus of the adhesive film for metal terminals is 700 MPa or less. The base material is the layer having the highest Martens hardness measured in a direction perpendicular to the cross-section in the thickness direction of the layer among the layers located between the first polyolefin layer and the second polyolefin layer. The absolute value of the difference between the Martens hardness measured in a direction perpendicular to the cross-section in the thickness direction of the base material and the Martens hardness measured in a direction perpendicular to the cross-section in the thickness direction of the first polyolefin layer is 10 N / mm 2 is as follows, A method for manufacturing an adhesive film for metal terminals, which includes a colored layer between the second polyolefin layer and the base material.

12. A metal terminal with an adhesive film for metal terminals, wherein the adhesive film for metal terminals according to claim 1 or 2 is attached to the metal terminal.

13. A power storage device including at least a power storage device element including a positive electrode, a negative electrode, and an electrolyte, an exterior material for the power storage device that seals the power storage device element, and metal terminals electrically connected to the positive electrode and the negative electrode respectively and protruding outside the exterior material for the power storage device, A power storage device, wherein the adhesive film for metal terminals according to claim 1 or 2 is interposed between the metal terminal and the exterior material for the power storage device.

14. A method for manufacturing a power storage device including at least a power storage device element including a positive electrode, a negative electrode, and an electrolyte, an exterior material for the power storage device that seals the power storage device element, and metal terminals electrically connected to the positive electrode and the negative electrode respectively and protruding outside the exterior material for the power storage device, A method for manufacturing a power storage device, comprising a step of interposing the adhesive film for metal terminals according to claim 1 or 2 between the metal terminal and the exterior material for the power storage device, and sealing the power storage device element with the exterior material for the power storage device.

15. An exterior material for a power storage device for use in a power storage device, wherein the power storage device includes at least a power storage device element including a positive electrode, a negative electrode, and an electrolyte, an exterior material for the power storage device that seals the power storage device element, and metal terminals that are electrically connected to the positive electrode and the negative electrode respectively and protrude outside the exterior material for the power storage device, and an adhesive film for metal terminals is interposed between the metal terminals and the exterior material for the power storage device. The adhesive film for metal terminals is the adhesive film for metal terminals according to claim 1 or 2. The exterior material for the power storage device is composed of a laminate including at least a base material layer, a barrier layer, and a heat-sealable resin layer.

16. A kit including an exterior material for a power storage device for use in a power storage device and the adhesive film for metal terminals according to claim 1 or 2, wherein the power storage device includes at least a power storage device element including a positive electrode, a negative electrode, and an electrolyte, an exterior material for the power storage device that seals the power storage device element, and metal terminals that are electrically connected to the positive electrode and the negative electrode respectively and protrude outside the exterior material for the power storage device. The kit is used such that the adhesive film for metal terminals is interposed between the metal terminals and the exterior material for the power storage device during use.

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