JP7816615B2 - Quality control method in molding process of exterior material for power storage device, manufacturing method of power storage device, exterior material for power storage device, and power storage device - Google Patents

Description

This disclosure relates to a quality control method in the molding process of an exterior material for an electricity storage device, a manufacturing method for an electricity storage device, an exterior material for an electricity storage device, and an electricity storage device.

Various types of electricity storage devices have been developed to date, but in all of these devices, exterior materials are essential components for sealing the electricity storage device elements, such as electrodes and electrolytes. Traditionally, metal exterior materials have been widely used as exterior materials for electricity storage devices.

On the other hand, in recent years, with the increasing performance of electric vehicles, hybrid electric vehicles, personal computers, cameras, mobile phones, and other devices, there has been a demand for energy storage devices to be thinner and lighter, as well as have a variety of shapes. However, the metal exterior materials for energy storage devices that have traditionally been widely used have the drawback of being difficult to adapt to the increasing variety of shapes, and there are also limitations to how light they can be made.

In recent years, therefore, film-like laminates, in which a base layer, a barrier layer, and a heat-sealable resin layer are sequentially laminated, have been proposed as packaging materials for electricity storage devices that can be easily processed into a variety of shapes and can be made thinner and lighter (see, for example, Patent Document 1).

In such electrical storage device packaging materials, recesses are generally formed by cold forming, and electrical storage device elements such as electrodes and electrolyte are placed in the spaces formed by the recesses. The heat-sealable resin layer is then heat-sealed to obtain an electrical storage device in which the electrical storage device elements are housed inside the electrical storage device packaging material.

Japanese Patent Application Laid-Open No. 2008-287971

In an electrical storage device packaging material formed from the above-described film-like laminate, the formation of a recess for accommodating an electrical storage device element forms a bent portion in the electrical storage device packaging material. Because the electrical storage device packaging material is stretched at this bent portion, whitening may occur on the surface. Whitening due to molding of the electrical storage device packaging material can lead to poor appearance of the electrical storage device, and is therefore subject to quality control during molding of the electrical storage device packaging material. During this quality control, for example, if the electrical storage device packaging material is colored or if the degree of whitening is significant, the presence or absence of whitening can be visually confirmed.

However, through investigations, the inventors have found that although whitening is difficult to detect visually at the bent portions that form the recesses in the exterior material for an electricity storage device, when the bent portions (the curved portions on the outer surface of the exterior material for an electricity storage device) are observed using a scanning electron microscope or similar, very fine cracks may be found to have formed. Therefore, it has become clear that a new quality control method is needed in the molding process of exterior materials for electricity storage devices.

In light of these circumstances, the primary objective of this disclosure is to provide a new quality control method for the molding process of exterior materials for electricity storage devices.

The inventors of the present disclosure conducted extensive studies to solve the above-mentioned problems. As a result, they found that, in a molding process of an electrical storage device exterior material, a test electrical storage device exterior material is extracted from electrical storage device exterior materials having recesses formed therein, and the L* value in the L*a*b ^* color space of reflected light is measured for each of the curved and uncurved portions of the outer surface that form the recesses of the test electrical storage ^device exterior material under measurement conditions of the ^SCI method, a field of view of ¹⁰ °, and light source ^F2 , and whether or not the electrical storage device exterior material having recesses formed therein is a non-defective product is determined based on the magnitude of the difference in the L ^* values (i.e., the absolute value of the difference in the L* values), thereby enabling quality control with higher accuracy than conventional visual determination.

The present disclosure has been completed based on these findings and further investigations. That is, the present disclosure provides the inventions of the following aspects.
A quality control method in a molding process of an exterior material for an electricity storage device, comprising:
The quality control method targets quality control of an electrical storage device packaging material that is made of a laminate including at least, in order from the outside, a base material layer, a barrier layer, and a heat-sealable resin layer, and that is molded so as to protrude from the heat-sealable resin layer side toward the base material layer side, and that has a recess formed on the heat-sealable resin layer side in which an electrical storage device element is housed,
The method comprises a determination step of extracting a test-target electrical storage device exterior material from among the electrical storage device exterior materials having recesses formed therein, measuring the L* value in the L ^* a ^* b ^* color space of reflected light for each of the curved and ^{uncurved portions of the outer surface forming the recesses of the test-target electrical storage device exterior material under measurement conditions of an SCI method, a field of view of 10°, and a light source F2, and determining whether the electrical storage device exterior material having recesses formed therein is a non-defective product based on the magnitude of the difference in the L* value} .
A quality control method for the molding process of exterior materials for electricity storage devices.

The present disclosure can provide a novel quality control method for the molding process of an exterior material for an electricity storage device. The present disclosure can also provide a manufacturing method for an exterior material for an electricity storage device that utilizes the quality control method. The present disclosure can also provide an exterior material for an electricity storage device that is determined to be a non-defective product by the quality control method, and an electricity storage device that utilizes the exterior material for an electricity storage device.

1 is a schematic cross-sectional view showing an example of a laminated structure of an exterior packaging material for an electricity storage device according to the present disclosure. 1 is a schematic cross-sectional view showing an example of a laminated structure of an exterior packaging material for an electricity storage device according to the present disclosure. 1 is a schematic cross-sectional view showing an example of a laminated structure of an exterior packaging material for an electricity storage device according to the present disclosure. 1 is a schematic cross-sectional view showing an example of a laminated structure of an exterior packaging material for an electricity storage device according to the present disclosure. 1 is a schematic diagram showing a plan view of an exterior packaging material for an electricity storage device according to the present disclosure. FIG. 6 is a schematic cross-sectional view (lamination structure omitted) taken along line AA' in FIG. 5. 1 is an image obtained by observing the curved surface portion of the formed exterior material for an electricity storage device obtained in Example 1 with a scanning electron microscope (SEM). 10 is an image obtained by observing the curved surface portion of the exterior material for an electricity storage device after molding obtained in Example 2 with a scanning electron microscope (SEM). 10 is an image obtained by observing the curved surface portion of the formed exterior material for an electricity storage device obtained in Example 3 with a scanning electron microscope (SEM). 10 is an image obtained by observing the curved surface portion of the exterior material for an electricity storage device after molding obtained in Example 6 with a scanning electron microscope (SEM). FIG. 2 is a schematic diagram illustrating a method for housing an electricity storage device element in a package formed from the exterior packaging material for an electricity storage device of the present disclosure.

The quality control disclosed herein is a quality control method in a molding process of an electrical storage device exterior material, and the quality control method targets electrical storage device exterior materials in which the electrical storage device exterior material is composed of a laminate including, in order from the outside, a base material layer, a barrier layer, and a heat-sealable resin layer, and is molded so as to protrude from the heat-sealable resin layer side toward the base material layer side, and in which a recess for accommodating an electrical storage device element is formed on the heat-sealable resin layer side.The quality control method is characterized by comprising a determination step of selecting a test electrical storage device exterior material from the electrical storage device exterior materials in which a recess is formed, measuring the L ^* value in the L ^* a ^* b ^* color space of reflected light for each of the curved and uncurved portions on the outer surface that form the recess of the test electrical storage device exterior material under measurement conditions of the SCI method, a field of view of 10°, and a light source F2, and determining whether the electrical storage device exterior material in which a recess is formed is a non-defective product based on the magnitude of the difference in the L ^* values. According to the quality control method of the present disclosure, it is possible to determine whether or not an electrical storage device packaging material having recesses formed therein is a non-defective product based on the magnitude of the difference in L ^* value.

The quality control method for the molding process of the electrical storage device exterior material, the manufacturing method for the electrical storage device, the electrical storage device exterior material, and the electrical storage device disclosed herein are described in detail below. Note that in this specification, numerical ranges indicated by "to" mean "greater than or equal to" or "less than or equal to." For example, the expression "2 to 15 mm" means 2 mm or greater and 15 mm or less.

1. Quality Control Method The quality control method disclosed herein is a quality control method for a molding process of an electrical storage device packaging material. In the quality control method disclosed herein, the electrical storage device packaging material to be quality controlled is composed of a laminate including, from the outside, at least a base material layer, a barrier layer, and a heat-sealable resin layer. The laminate structure and each layer of the electrical storage device packaging material will be described in detail below.

Furthermore, in the quality control method disclosed herein, the electrical storage device packaging material that is the subject of quality control is molded so that it protrudes from the heat-sealable resin layer side toward the base layer side, and a recess in which the electrical storage device element is housed is formed on the heat-sealable resin layer side. In other words, the electrical storage device packaging material has a recess formed by molding. As described below, this molding can be performed using a mold or the like.

The shape of the recess formed in the exterior material for an electric storage device is not particularly limited, as long as it provides a space large enough to accommodate an electric storage device element. Specific examples of the recess shape include a generally rectangular or circular shape when viewed from the base layer 1 side. Figures 5 and 6 show schematic diagrams of a recess 100 having a rectangular shape in plan view provided in an exterior material 10 for an electric storage device. The rectangular shape in plan view includes not only rectangular corners but also rounded shapes, as shown in Figures 5 and 6. For example, in the rectangular recess shown in the schematic diagrams of Figures 5 and 6, the curved surface 11 includes corners 11a and ridges 11b that protrude toward the base layer 1, and the surfaces of the corners 11a and ridges 11b facing the base layer 1 each have a predetermined radius of curvature R. The rectangular recess 100 in plan view forms a rectangular parallelepiped space in which an electric storage device element is accommodated. If the recess has a circular shape in plan view, the recess forms a cylindrical space in which the energy storage device element is housed.

The size of the recess 100 is not particularly limited and is designed appropriately depending on the size of the electricity storage device (i.e., the size of the electricity storage device element to be housed). For example, if the recess is rectangular in plan view, when the electricity storage device exterior material 10 is observed from the base layer 1 side, the length of the long side of the recess 100 is, for example, approximately 20 mm or more, preferably approximately 30 mm or more, and more preferably approximately 50 mm or more. The length of the long side of the recess 100 is, for example, approximately 600 mm or less, preferably approximately 400 mm or less, and more preferably approximately 200 mm or less. Preferred ranges for the length of the long side of the recess 100 include approximately 20 to 600 μm, approximately 20 to 400 μm, approximately 20 to 200 μm, approximately 30 to 600 μm, approximately 30 to 400 μm, approximately 30 to 200 μm, approximately 50 to 600 μm, approximately 50 to 400 μm, and approximately 50 to 200 mm. Furthermore, when the exterior material 10 for an electricity storage device is observed from the base layer 1 side, the length of the short side of the recess 100 is, for example, about 10 mm or more, preferably about 20 mm or more, and more preferably about 30 mm or more. The length of the short side of the recess 100 is, for example, about 300 mm or less, preferably about 200 mm or less, and more preferably about 100 mm or less. Preferred ranges for the length of the short side of the recess 100 include about 10 to 300 μm, about 10 to 200 μm, about 10 to 100 μm, about 20 to 300 μm, about 20 to 200 μm, about 20 to 100 μm, about 30 to 300 μm, about 30 to 200 μm, and about 30 to 100 mm. The length of the long side and the length of the short side of the recess 100 may be the same (i.e., the shape of the recess 100 is square in a plan view).

The depth D of the recess 100 (see Figure 6) is not particularly limited and is designed appropriately depending on the size of the electricity storage device (i.e., the size of the electricity storage device elements to be housed), etc. For example, for an exterior packaging material 10 for an electricity storage device having a total thickness described below, the depth may be approximately 4 to 10 mm.

The recess 100 provided in the electricity storage device exterior material 10 is formed by molding the film-like electricity storage device exterior material. Specifically, using a mold (female mold) placed on the base material layer 1 side of the laminate constituting the electricity storage device exterior material and a mold (male mold) placed on the heat-sealable resin layer 4 side, the laminate is molded (typically cold-molded) so that it protrudes from the heat-sealable resin layer 4 side toward the base material layer 1 side, thereby forming the recess 100 on the heat-sealable resin layer 4 side in which the electricity storage device element is housed.

The quality control method of the present disclosure is characterized by including a determination step of determining whether or not an electrical storage device exterior material having a recess formed therein is a non-defective product. In the determination step, an electrical storage device exterior material to be tested is extracted from electrical storage device exterior materials 10 having recesses 100 formed therein, and the L* value in the L ^* a ^* b ^* color space of reflected light is measured for each of curved portion 11 and uncurved portion 12 on the outer surface that form the recess of the electrical storage device exterior material to be tested under measurement conditions of the SCI method, a field of view of 10° ^{, and light source F2, and whether or not the electrical storage device exterior material having recesses formed therein is a non-defective product is determined based on the magnitude of the difference in the L* values} . When the quality control method of the present disclosure is used as part of the manufacturing process of an electricity storage device, the electrical storage device exterior materials to be tested may be selected randomly, or at a predetermined rate (for example, one in every 1,000 to 10,000 electrical storage device exterior materials having a recess formed therein may be selected as the electrical storage device exterior material to be tested), or all electrical storage device exterior materials having a recess formed therein may be selected as the electrical storage device exterior materials to be tested. When all electrical storage device exterior materials having a recess formed therein are selected as the electrical storage device exterior materials to be tested, it is desirable to automate the measurement of the L ^* value and incorporate it into the production line, taking into account the production efficiency of the electricity storage device.

As described above, forming the recesses that accommodate the energy storage device elements forms bent portions (see curved portions 11 and 13 in Figure 6 ) in the energy storage device exterior material. Because the energy storage device exterior material is stretched during molding, these bent portions may whiten on the surface. Because whitening during molding of the energy storage device exterior material leads to poor appearance of the energy storage device, it is subject to quality control during molding of the energy storage device exterior material. During this quality control, for example, when the energy storage device exterior material is colored or the degree of whitening is significant, the presence or absence of whitening can be confirmed visually. However, the inventors' investigations have found that, although whitening is not visually confirmed in the bent portions that form the recesses in the energy storage device exterior material, observation of the bent portions (curved portions on the outer surface of the energy storage device exterior material) using a scanning electron microscope or the like can reveal the formation of very fine cracks. Therefore, it is desirable to further improve the accuracy of quality control methods during the molding process of the energy storage device exterior material.

In the quality control method of the present disclosure, it is possible to suitably detect the quality, such as whether or not fine cracks are formed in the curved surface portion of the recess formed by molding, based on the magnitude of the difference in L ^* value (i.e., the absolute value of the difference in L ^* value). Therefore, if the quality control method of the present disclosure is used in the manufacture of an electricity storage device, it is possible to appropriately set an evaluation standard for the magnitude of the difference in L ^* value according to the quality required of the electricity storage device, and suitably prevent the production of defective products in the molding process of the exterior material for the electricity storage device.

The evaluation criteria for the difference in L ^* value can be set appropriately depending on the quality required for the electricity storage device. For example, from the viewpoint of controlling whitening in the curved surface portion 11, the absolute value of the difference between the L ^* value of the curved surface portion 11 and the L ^* value of the non-curved surface portion 12 (the absolute value of the difference that is determined to be a non-defective product) is preferably 2.0 or less, more preferably 1.8 or less, even more preferably 1.5 or less, even more preferably 1.0 or less, still more preferably 0.5 or less, and particularly preferably 0.3 or less. From this viewpoint, preferred ranges for the absolute value of the difference between the L ^* value of the curved surface portion 11 and the L ^* value of the non-curved surface portion 12 include approximately 0.0 to 2.0, approximately 0.0 to 1.8, approximately 0.0 to 1.5, approximately 0.0 to 1.0, approximately 0.0 to 0.5, and approximately 0.0 to 0.3.

When forming recesses in an electrical storage device exterior material, the greatest strain is applied to the bent portions, making them prone to microcracks. For example, cracks occurring in layers constituting the electrical storage device exterior material, such as the surface coating layer, can create gaps, exposing the gloss of the underlying surface and increasing the L ^* value of the curved portions compared to the non-curved portions. For example, even in an electrical storage device exterior material with excellent electrolyte resistance, if microcracks occur in the curved portions formed by molding, the electrolyte can penetrate through the microcracks, leading to peeling of the exterior material. To design an electrical storage device exterior material that reduces the difference in L ^* value, a hard electrical storage device exterior material cannot conform to molding and cracks can occur, so this can be adjusted by making the material flexible despite its hardness. Furthermore, even if the electrical storage device exterior material is hard and flexible, the presence of a large amount of additives such as wax or particles can weaken the adhesion at the boundary between the resin and particles or the resin and wax, making it more likely to crack from the boundary. Therefore, it is preferable to adjust the content of additives to the minimum necessary.

Furthermore, in an electricity storage device, for example, if fine cracks are formed in the curved surface portion 11 of the electricity storage device exterior material 10, depending on the extent of the cracks, when an electrolyte solution is applied to the surface of the electricity storage device exterior material during the manufacturing process of the electricity storage device, the electrolyte solution may penetrate into the cracks, causing delamination between the layers constituting the electricity storage device exterior material. From the viewpoint of performing quality control so as to manufacture an electricity storage device with excellent electrolyte resistance, in the judgment process, it is desirable to control the absolute value of the difference between the L ^* value of the curved surface portion 11 and the L ^* value of the non-curved surface portion 12 (the absolute value of the difference that is judged to be a good product) under stricter conditions than those for the whitening described above, and is preferably 1.5 or less, more preferably 1.0 or less, even more preferably 0.5 or less, and particularly preferably 0.3 or less. Note that the absolute value of the difference between the L ^* value of the curved surface portion 11 and the L ^* value of the non-curved surface portion 12 is 0.0 or more. Preferred ranges for the absolute value of the difference between the L ^* value of the curved surface portion 11 and the L ^* value of the uncurved surface portion 12 include approximately 0.0 to 1.5, approximately 0.0 to 1.0, approximately 0.0 to 0.5, and approximately 0.0 to 0.3. From a similar perspective, a preferred range for the absolute value of the difference between the a ^* value of the curved surface portion 11 and the a ^* value of the uncurved surface portion 12 (i.e., the absolute value of the difference that determines a product is good) is approximately 0.00 to 0.12. From a similar perspective, a preferred range for the absolute value of the difference between the b ^* value of the curved surface portion and the b ^* value of the uncurved surface portion (i.e., the absolute value of the difference that determines a product is good) is approximately 0.00 to 0.60. From a similar perspective, the ΔE ^* ab value is preferably approximately 1.8 or less, more preferably approximately 1.0 or less. Furthermore, preferred ranges for the ΔE ^* ab value include approximately 0.0 to 1.8, and approximately 0.0 to 1.0. The ΔE ^* ab value can be calculated based on the formula ΔE ^* ab=[(ΔL) ² +(Δa) ² +(Δb) ² ] ^1/2 .

In the present disclosure, the determination step can be specifically carried out as follows. The L* value in the L*a*b* color space is measured under the following conditions for each of the curved portions 11 on the outer surface of the electrical storage device exterior material on the side of the base material 1 that forms the recess 100, the curved portions 11 protruding toward the base material 1 of the electrical storage device exterior material 10, ^and the uncurved portions 12 on the outer surface of the base material 1 that forms the recess 100 (the uncurved portions 12 shown in the schematic diagrams of ^FIGS . ⁵ and ⁶ ). The observation conditions of a spectrophotometer (for example, a spectrophotometer (CM-700d) manufactured by Konica Minolta) calibrated with a white calibration cap (for example, a CM-A177 manufactured by Konica Minolta) are set to 10°, an observation illuminant to F2, and SCI mode (JIS Z8722-2009). Next, the L ^* value of the outer surface (surface on the substrate layer 1 side) of each of the curved surface portion 11 and the non-curved surface portion 12 to be measured is measured at room temperature and normal humidity. The measurement diameter is set to 8 mmφ for the curved surface portion 11, and to 3 mmφ for the non-curved surface portion 12. The a ^* value and b ^* value of each of the curved surface portion 11 and the non-curved surface portion 12 can also be measured under these measurement conditions together with the L ^* value.

The curved surface portion 11 to be measured for the L ^* value is the portion of the curved surface portion 11 forming the recess 100 that is most stretched by molding (the molding process for forming the recess 100) (i.e., the portion most likely to develop fine cracks). The most stretched portion is the portion where the difference in L ^* value is greatest, and is also the portion of the curved surface portion 11 where the L ^* value of the curved surface portion 11 is greatest. For example, in the case of a recess 100 having a rectangular shape in plan view as shown in the schematic diagrams of Figures 5 and 6, the corner portion 11a is the portion of the curved surface portion 11 (rectangular shape in plan view) that is most stretched, so it is preferable to measure the L ^* value of the corner portion 11a. Note that there are four corner portions 11a in the shape of the molding die. However, if the shapes of the four corners of the die that form the corner portions 11a are the same, the L ^* values of the corner portions 11a will also be substantially the same. Therefore, if the L ^* value of one corner portion 11a is measured, it is possible to omit measuring the L ^* values of the other three corner portions 11a. The curved surface portion 11 for measuring the a ^* value and the b ^* value is the same as the curved surface portion 11 for measuring the L ^* value.

Furthermore, depending on the shape of the mold, even in a recess having a rectangular shape in plan view, such as those shown in the schematic diagrams of Figures 5 and 6, the ridge portion 11b of the curved surface portion 11 protruding toward the substrate layer 1 may be the portion that is most stretched. For example, if the radius of curvature R of the ridge portion 11b on the surface facing the substrate layer 1 is smaller than the radius of curvature R of the corners 11a, the ridge portion 11b of the curved surface portion 11 protruding toward the substrate layer 1 may be the portion that is most stretched. In such cases, it is preferable to measure the ridge portion 11b as the object of measurement for the L ^* value. Furthermore, for example, in a recess having a circular shape in plan view, since there are no corners, the ridge portion is the object of measurement for the L ^* value. Note that the curved surface portion 13 in Figure 6 is a curved surface portion that does not protrude toward the substrate layer 1. Compared to the curved surface portion 11 protruding toward the substrate layer 1, it typically undergoes less stretching due to molding, and may or may not be used as the curved surface portion 11 that is the object of measurement for the L ^* value.

Furthermore, the L ^* value of the non-curved surface portion is preferably measured by taking the portion that is not substantially stretched by molding as the non-curved surface portion 12. The L ^* value of the non-curved surface portion is usually the same at any position, but when the recess 100 is observed from the base layer 1 side, for example, it is preferable to measure the L ^* value by taking the center portion of the recess 100 as the non-curved surface portion 12.

In the quality control method of the present disclosure, the L ^* value of the curved surface portion 11 and the L ^* value of the non-curved surface portion 12 of the electrical storage device exterior material 10, which are the subject of quality control, are not particularly limited, and it is sufficient to appropriately control the difference between these L ^* values from the viewpoints of whitening, electrolyte resistance, etc., as described above. For example, when the electrical storage device exterior material 10 is colored (specifically, when at least one layer (e.g., the base material layer 1, adhesive layer 2, colored layer, surface coating layer 6, etc., described below) of the layers located closer to the base material layer 1 than the barrier layer 3 of the electrical storage device exterior material 10 is colored, and a color different from that of the barrier layer 3 is visually recognized when the electrical storage device exterior material 10 is observed from the base material layer 1 side), whitening or the like in the curved surface portion 11 is likely to result in the product being determined to be defective, and the quality control method of the present disclosure is preferably used particularly when the external appearance of the electrical storage device exterior material 10 is a dark color such as black.

From this perspective, the L ^* value of the uncurved surface portion 12 of the exterior material 10 for an electricity storage device, which is subject to quality control, is preferably, for example, about 60.0 or less, more preferably about 50.0 or less, even more preferably about 40.0 or less, and even more preferably about 30.0 or less. The L ^* value of the uncurved surface portion 12 is, for example, about 0.0 or more, about 10.0 or more, or about 20.0 or more. Preferred ranges for the L ^* value of the non-curved surface portion 12 include approximately 0.0 to 60.0, approximately 0.0 to 50.0, approximately 0.0 to 40.0, approximately 0.0 to 30.0, approximately 10.0 to 60.0, approximately 10.0 to 50.0, approximately 10.0 to 40.0, approximately 10.0 to 30.0, approximately 20.0 to 60.0, approximately 20.0 to 50.0, approximately 20.0 to 40.0, and approximately 20.0 to 30.0. Similarly, the a ^* value of the non-curved surface portion 12 is, for example, approximately +2.00 or less, preferably approximately +1.00 or less. Furthermore, the a ^* value of the non-curved surface portion 12 is, for example, approximately -2.00 or more, preferably approximately -1.00 or more. Preferred ranges for the a ^* value of the non-curved surface portion 12 include approximately -2.00 to +2.00, approximately -2.00 to +1.00, approximately -1.00 to +2.00, and approximately -1.00 to +1.00. Similarly, the b ^* value of the non-curved surface portion 12 is, for example, approximately +1.00 or less, and preferably approximately +0.00 or less. Furthermore, the b ^* value of the non-curved surface portion 12 is, for example, approximately -3.00 or more, and preferably approximately -2.00 or more. Preferred ranges for the b ^* value of the non-curved surface portion 12 include approximately -3.00 to +1.00, approximately -3.00 to +0.00, approximately -2.00 to +1.00, and approximately -2.00 to +0.00.

The difference between the L ^* value of the curved surface portions 11 and the L ^* value of the non-curved surface portions 12 is adjusted to a predetermined value, for example, by adjusting the composition, thickness, etc. of the layer located at the outermost layer of the electrical storage device exterior material 10 (for example, the substrate layer 1 and the surface coating layer 6 described below), the shape, size, surface roughness, etc. of the mold, and the pressing pressure of the mold, etc. Furthermore, as described below, the difference between the L ^* value of the curved surface portions 11 and the L ^* value of the non-curved surface portions 12 may be adjusted by adjusting the lamination conditions, etc. of each layer in the lamination process of the electrical storage device exterior material 10.

Furthermore, for example, when the exterior material for an electricity storage device has a matte finish, whitening on the curved surface portion 11 is likely to lead to the product being determined to be defective, and therefore the quality control method disclosed herein is preferably used. From this perspective, the specular gloss of the uncurved surface portion 12 of the exterior material for an electricity storage device 10 that is the subject of quality control is preferably, for example, approximately 5.0 or less, and more preferably approximately 3.6 or less. The specular gloss is, for example, approximately 1.0 or more. Preferred ranges for the specular gloss include approximately 1.0 to 5.0, and approximately 1.0 to 3.6. The specular gloss of the uncurved surface portion 12 of the exterior material for an electricity storage device 10 is determined as follows. The specular gloss of the uncurved portion of the electrical storage device exterior material in which a recess is formed is substantially the same as the specular gloss of the outer surface of the electrical storage device exterior material before molding (the position that will become the uncurved portion after molding) (that is, the specular gloss of the uncurved portion does not substantially change due to molding; however, for example, when the recess 100 is observed from the base layer 1 side, it is preferable to measure the specular gloss using the center portion of the recess 100 as the uncurved portion 12). Therefore, if an unmolded electrical storage device exterior material is available, the specular gloss of the outer surface of the unmolded electrical storage device exterior material may be measured using the following measurement method.

<Measurement of specular gloss>
The specular gloss of the outer surface of the uncurved portion of the exterior material for an electrical storage device is measured by the following method: The specular gloss of the surface coating layer is measured at an incident angle of 60 degrees using a gloss meter (for example, a gloss meter, Micro-Tri-Gloss (measurement area 9 mm × 15 mm), manufactured by Toyo Seiki Seisakusho, Ltd.) in accordance with the method specified in JIS Z 8741 (1997).

As described above, the quality control method disclosed herein is a novel quality control method that includes a determination step of determining whether an electrical storage device exterior material having a recess formed therein is a non-defective product based on the magnitude of the L ^* values of the curved and uncurved portions that form the recess during the molding process of the electrical storage device exterior material. This allows for more accurate quality control compared to conventional quality control using visual inspection or a camera. Therefore, by utilizing the quality control method disclosed herein in the manufacture of an electrical storage device, it becomes possible to more efficiently manufacture non-defective electrical storage devices. The determination step can be used as a determination method for evaluating the characteristics (molding characteristics) of an electrical storage device exterior material based on, for example, whether the electrical storage device exterior material has fine cracks formed in the layers that constitute the electrical storage device exterior material due to molding when the recess is formed. By using this determination method, the characteristics of an electrical storage device exterior material can be easily evaluated without using a scanning electron microscope or the like.

2. Manufacturing Method of Electricity Storage Device The manufacturing method of an electricity storage device according to the present disclosure is a manufacturing method of an electricity storage device in which an electricity storage device element is sealed with a packaging body formed by heat-sealing the heat-sealable resin layer 4 at the periphery (e.g., peripheral portion 14 in Figures 5 and 6 ) of an exterior packaging material 10 for an electricity storage device, which is composed of a laminate including, in this order from the outside, at least a base material layer 1, a barrier layer 3, and a heat-sealable resin layer 4. The manufacturing method of an electricity storage device according to the present disclosure utilizes the quality control method described in the section "1. Quality Control Method" above in the manufacture of an electricity storage device, and therefore, description of overlapping matters will be omitted as appropriate. As mentioned above, the laminate structure and each layer of the exterior packaging material for an electricity storage device will be described in detail below.

The manufacturing method for an electricity storage device disclosed herein includes a step of preparing an electrical storage device packaging material having a recess formed therein for accommodating an electricity storage device element, the recess protruding from the heat-sealable resin layer side of the electrical storage device packaging material toward the base layer side. The electrical storage device packaging material having such a recess formed therein is as explained above in the section "1. Quality control method," and therefore further explanation is omitted here.

The manufacturing method for an electricity storage device according to the present disclosure also includes a determination step in which a test electricity storage device exterior material is selected from among the electricity storage device exterior materials having recesses formed therein, and the L* value in the L ^* a ^* b ^* color space of reflected light is measured for each of the curved and uncurved portions of the outer surface forming the recesses of the test electricity storage device exterior material using the ^SCI method, a field of view of 10°, and measurement conditions of light source F2, and whether the electricity storage device exterior material having recesses formed therein is a non-defective product is determined based on the magnitude of the difference in the L ^* values. The determination step is also as described in the section "1. Quality Control Method" above, and therefore further description will be omitted. Note that if the electricity storage device exterior material having recesses formed therein is determined to be a defective product in the determination step of the manufacturing method for an electricity storage device according to the present disclosure, the process returns to the lamination step of the electricity storage device exterior material and the molding step of the electricity storage device exterior material, and the configuration, lamination method, molding conditions, etc. of the electricity storage device exterior material are adjusted until the product is determined to be a non-defective product in the determination step.

The method for manufacturing an electricity storage device disclosed herein includes a step of manufacturing an electricity storage device by accommodating an electricity storage device element in a recess in an exterior material for an electricity storage device. In the method for manufacturing an electricity storage device disclosed herein, if the result of the determination step indicates that the exterior material for an electricity storage device in which a recess is formed is a non-defective product, it is determined that the formation of the recess is appropriate, and an electricity storage device element is accommodated in the recess to manufacture the electricity storage device.

As described above, the evaluation criteria for the difference in L ^* value can be set appropriately depending on the quality required for the electricity storage device. For example, from the viewpoint of controlling whitening in the curved surface portion 11, the absolute value of the difference between the L ^* value of the curved surface portion 11 and the L ^* value of the non-curved surface portion 12 (the absolute value of the difference that is determined to be a non-defective product) is preferably 2.0 or less, more preferably 1.8 or less, even more preferably 1.5 or less, even more preferably 1.0 or less, still more preferably 0.5 or less, and particularly preferably 0.3 or less. From this viewpoint, preferred ranges for the absolute value of the difference between the L ^* value of the curved surface portion 11 and the L ^* value of the non-curved surface portion 12 include approximately 0.0 to 2.0, approximately 0.0 to 1.8, approximately 0.0 to 1.5, approximately 0.0 to 1.0, approximately 0.0 to 0.5, and approximately 0.0 to 0.3.

Furthermore, as described above, from the viewpoint of quality control so as to manufacture an electricity storage device with excellent electrolyte resistance, in the determination step, it is desirable to control the absolute value of the difference between the L ^* value of the curved surface portion 11 and the L ^* value of the non-curved surface portion 12 (the absolute value of the difference that determines that the product is good) under stricter conditions than those for the whitening described above, and it is preferably 1.5 or less, more preferably 1.0 or less, even more preferably 0.5 or less, and particularly preferably 0.3 or less. The absolute value of the difference between the L ^* value of the curved surface portion 11 and the L ^* value of the non-curved surface portion 12 is 0.0 or more. Preferred ranges for the absolute value of the difference between the L ^* value of the curved surface portion 11 and the L ^* value of the non-curved surface portion 12 include approximately 0.0 to 1.5, approximately 0.0 to 1.0, approximately 0.0 to 0.5, and approximately 0.0 to 0.3. From the same viewpoint, the absolute value of the difference between the a ^* value of the curved surface portion 11 and the a ^* value of the non-curved surface portion 12 (i.e., the absolute value of the difference at which the product is determined to be non-defective) is preferably in the range of about 0.00 to 0.12. From the same viewpoint, the absolute value of the difference between the b ^* value of the curved surface portion and the b ^* value of the non-curved surface portion (i.e., the absolute value of the difference at which the product is determined to be non-defective) is preferably in the range of about 0.00 to 0.60.

A known method can be used to house the electricity storage device element in the recess 100 and manufacture the electricity storage device. Specifically, the electrodes, electrolyte, and other components that make up the electricity storage device element are housed in the recess 100, and the heat-sealable resin layers 4 of the electricity storage device exterior material 10 are heat-sealed to each other, thereby sealing the electricity storage device element and obtaining the electricity storage device.

3. Inspection Method The inspection method of the present disclosure is a method for inspecting an electrical storage device packaging material having a recess formed therein. The inspection method of the present disclosure inspects an electrical storage device packaging material that is composed of a laminate including, from the outside, at least a base layer, a barrier layer, and a heat-sealable resin layer, and that is molded so as to protrude from the heat-sealable resin layer side toward the base layer side, and that has a recess formed on the heat-sealable resin layer side in which an electrical storage device element is housed. The quality control method of the present disclosure described above can be said to be a quality control method that utilizes the inspection method of the present disclosure, and explanations of matters that overlap with those described in the section "1. Quality Control Method" above will be omitted as appropriate. As mentioned above, the laminate structure and each layer of the electrical storage device packaging material will be described in detail below.

In the inspection method disclosed herein, the electrical storage device packaging material with recesses formed therein that is the subject of inspection is as described above in the section "1. Quality control method," and so further description will be omitted.

The inspection method of the present disclosure also includes a determination step of measuring the L* value in the L*a*b ^* color space of reflected light for each of the curved and uncurved portions of the outer surface that form the recess of an electrical storage device packaging material having a recess formed therein, using the ^SCI method, a field of view of ¹⁰ °, and measurement conditions of light source ^F2 , and determining whether the electrical storage device packaging material having a recess formed therein is a non-defective product based on the magnitude of the difference in the L ^* values. The determination step is also as described in the section "1. Quality control method" above, and therefore further description will be omitted.

As described above, the evaluation criteria for the difference in L ^* value can be set appropriately depending on the quality required for the electricity storage device. For example, from the viewpoint of controlling whitening in the curved surface portion 11, the absolute value of the difference between the L ^* value of the curved surface portion 11 and the L ^* value of the non-curved surface portion 12 (the absolute value of the difference that is determined to be a non-defective product) is preferably 2.0 or less, more preferably 1.8 or less, even more preferably 1.5 or less, even more preferably 1.0 or less, still more preferably 0.5 or less, and particularly preferably 0.3 or less. From this viewpoint, preferred ranges for the absolute value of the difference between the L ^* value of the curved surface portion 11 and the L ^* value of the non-curved surface portion 12 include approximately 0.0 to 2.0, approximately 0.0 to 1.8, approximately 0.0 to 1.5, approximately 0.0 to 1.0, approximately 0.0 to 0.5, and approximately 0.0 to 0.3.

Furthermore, as described above, from the viewpoint of quality control so as to manufacture an electricity storage device with excellent electrolyte resistance, in the determination step, it is desirable to control the absolute value of the difference between the L ^* value of the curved surface portion 11 and the L ^* value of the non-curved surface portion 12 (the absolute value of the difference that determines that the product is good) under stricter conditions than those for the whitening described above, and it is preferably 1.5 or less, more preferably 1.0 or less, even more preferably 0.5 or less, and particularly preferably 0.3 or less. The absolute value of the difference between the L ^* value of the curved surface portion 11 and the L ^* value of the non-curved surface portion 12 is 0.0 or more. Preferred ranges for the absolute value of the difference between the L ^* value of the curved surface portion 11 and the L ^* value of the non-curved surface portion 12 include approximately 0.0 to 1.5, approximately 0.0 to 1.0, approximately 0.0 to 0.5, and approximately 0.0 to 0.3. From the same viewpoint, the absolute value of the difference between the a ^* value of the curved surface portion 11 and the a ^* value of the non-curved surface portion 12 (i.e., the absolute value of the difference at which the product is determined to be non-defective) is preferably in the range of about 0.00 to 0.12. From the same viewpoint, the absolute value of the difference between the b ^* value of the curved surface portion and the b ^* value of the non-curved surface portion (i.e., the absolute value of the difference at which the product is determined to be non-defective) is preferably in the range of about 0.00 to 0.60.

4. Electricity Storage Device Exterior Material The electricity storage device exterior material 10 of the present disclosure is an electricity storage device exterior material composed of a laminate including, in order from the outside, at least a base material layer 1, a barrier layer 3, and a heat-sealable resin layer 4. The electricity storage device exterior material 10 is formed so as to protrude from the heat-sealable resin layer 4 side toward the base material layer 1, and includes a recess 100 on the heat-sealable resin layer 4 side in which an electricity storage device element is housed. Furthermore, when the L* value in the L*a*b* color space of reflected light is measured for each of the curved surface portions 11 and the uncurved surface portions 12 on the outer surface that form the recess of the electricity ^{storage device exterior material 10 under measurement conditions of the SCI method, a field of view of 10°, and light source F2, the absolute value of the difference between the L* value of the curved} surface portions 11 and the L ^* of the uncurved surface portions 12 is 1.5 or less. That is, the exterior packaging material 10 for an electricity storage device according to the present disclosure is one of the exterior packaging materials 10 for an electricity storage device described above in "1. Quality control method" in which the absolute value of the difference between the L ^* value of the curved portion 11 and the L ^* value of the non-curved portion 12 is 1.5 or less. Therefore, a description of the shape and the like of the exterior packaging material 10 for an electricity storage device will be omitted.

As described above, if fine cracks are formed in the curved surface portions of the electrical storage device exterior material in an electrical storage device, depending on the severity of the cracks, when an electrolyte solution is applied to the surface of the electrical storage device exterior material during the manufacturing process of the electrical storage device, the electrolyte solution may penetrate into the cracks, causing delamination between the layers constituting the electrical storage device exterior material. Therefore, it is desirable to control the absolute value of the difference between the L ^* value of the curved surface portion 11 and the L ^* value of the non-curved surface portion 12 of the electrical storage device exterior material 10 having recesses under stricter conditions than those for the whitening. From this perspective, in the electrical storage device exterior material 10 of the present disclosure, the absolute value of the difference between the L ^* value of the curved surface portion 11 and the L ^* value of the non-curved surface portion 12 is set to a particularly low value of 1.5 or less. In the exterior packaging material 10 for an electricity storage device of the present disclosure, the absolute value of the difference between the L ^* value of the curved surface portion 11 and the L ^* value of the uncurved surface portion 12 is preferably 1.0 or less, more preferably 0.5 or less, and particularly preferably 0.3 or less. As described above, the absolute value of the difference between the L ^* value of the curved surface portion 11 and the L ^* value of the uncurved surface portion 12 is 0.0 or more. Preferred ranges for the absolute value of the difference between the L ^* value of the curved surface portion 11 and the L ^* value of the uncurved surface portion 12 include approximately 0.0 to 1.5, approximately 0.0 to 1.0, approximately 0.0 to 0.5, and approximately 0.0 to 0.3. From the same viewpoint, preferred ranges for the absolute value of the difference between the a ^* value of the curved surface portion 11 and the a ^* value of the uncurved surface portion 12 include approximately 0.00 to 0.12. From the same viewpoint, a preferable range of the absolute value of the difference between the b ^* value of the curved surface portion and the b ^* value of the non-curved surface portion is approximately 0.00 to 0.60. Details of the preferable L ^* value, a ^* value, and b ^* value of the curved surface portion 11 and the non-curved surface portion 12, as well as the measurement methods and measurement locations, are as explained above in "1. Quality control method."

Furthermore, in the present disclosure, the electrical storage device exterior packaging material 10 before the recess 100 is formed is molded under the following molding conditions so that the electrical storage device exterior packaging material protrudes from the heat-sealable resin layer 4 side toward the base layer 1 side, forming a recess on the heat-sealable resin layer 4 side in which an electrical storage device element is housed, and when the L* value in the L ^* a ^* b ^* color space of reflected light is measured for each of the curved portions 11 and the ^{uncurved portions 12 on the outer surface that form the recess of the electrical storage device exterior packaging material 10 using the SCI method, a field of view of 10°, and light source F2, the absolute value of the difference between the L* value} of the curved portions 11 and the L ^* of the uncurved portions 12 is preferably 1.5 or less. The electrical storage device exterior packaging material 10 does not have the aforementioned recess formed therein, and when a recess is formed under specified molding conditions, the absolute value of the difference between the L ^* value of the curved portions 11 and the L ^* of the uncurved portions 12 is 1.5 or less.

(Molding conditions)
The electrical storage device exterior material is placed between a molding die (female die) with a diameter of 54.5 mm (TD) x 31.6 mm (MD) and a corresponding molding die (male die) with the female die facing the substrate layer, and cold-formed at a pressing pressure (surface pressure) of 0.25 MPa and a molding depth of 3.0 mm to form a rectangular recess in plan view. The clearance between the female die and the male die is 0.5 mm. The surface of the female die has a maximum height roughness (nominal Rz value) of 0.8 μm, as specified in Table 2 of the comparative surface roughness standard specimen in JIS B 0659-1:2002, Appendix 1 (Reference). The corner R of the female die is 2.0 mm, and the ridge R is 2.5 mm. The surface of the male mold has a maximum height roughness (nominal Rz value) of 3.2 μm as specified in Table 2 of the comparative surface roughness standard specimen in Appendix 1 of JIS B 0659-1:2002 (reference). The corner R of the male mold is 2.0 mm, and the ridge R is 2.0 mm. The corner R and ridge R of the male mold have a maximum height roughness (nominal Rz value) of 1.6 μm as specified in Table 2 of the comparative surface roughness standard specimen in Appendix 1 of JIS B 0659-1:2002 (reference).

Even in such an unmolded exterior packaging material 10 for an electrical storage device, after recesses are formed under the molding conditions described above, the absolute value of the difference between the L ^* value of the curved surface portion 11 and the L ^* value of the uncurved surface portion 12 is preferably 1.0 or less, more preferably 0.5 or less, and particularly preferably 0.3 or less. As described above, the absolute value of the difference between the L ^* value of the curved surface portion 11 and the L ^* value of the uncurved surface portion 12 is 0.0 or more. Preferred ranges for the absolute value of the difference between the L ^* value of the curved surface portion 11 and the L ^* value of the uncurved surface portion 12 include approximately 0.0 to 1.5, approximately 0.0 to 1.0, approximately 0.0 to 0.5, and approximately 0.0 to 0.3. From the same viewpoint, preferred ranges for the absolute value of the difference between the a ^* value of the curved surface portion 11 and the a ^* value of the uncurved surface portion 12 include approximately 0.00 to 0.12. From the same viewpoint, a preferable range of the absolute value of the difference between the b ^* value of the curved surface portion and the b ^* value of the non-curved surface portion is approximately 0.00 to 0.60. Details of the preferable L ^* value, a ^* value, and b ^* value of the curved surface portion 11 and the non-curved surface portion 12, as well as the measurement methods and measurement locations, are as explained above in "1. Quality control method."

Laminated Structure of Electricity Storage Device Exterior Material As shown in FIG. 1 , for example, an electricity storage device exterior material 10 is composed of a laminate including at least a base material layer 1, a barrier layer 3, and a heat-sealable resin layer 4 in this order. In the electricity storage device exterior material 10, the base material layer 1 is the outermost layer, and the heat-sealable resin layer 4 is the innermost layer. When assembling an electricity storage device using the electricity storage device exterior material 10 and an electricity storage device element, the heat-sealable resin layers 4 of the electricity storage device exterior material 10 are placed opposite each other, and the peripheral portions 14 are heat-sealed to form a space, in which the electricity storage device element is housed. In the laminate constituting the electricity storage device exterior material 10 of the present disclosure, with the barrier layer 3 as the reference, the heat-sealable resin layer 4 side is on the inner side relative to the barrier layer 3, and the base material layer 1 side is on the outer side relative to the barrier layer 3.

As shown in Figures 2 to 4, the exterior packaging material 10 for an electricity storage device may optionally have an adhesive layer 2 between the base layer 1 and the barrier layer 3 to improve adhesion between these layers. As shown in Figures 3 and 4, an adhesive layer 5 may optionally be provided between the barrier layer 3 and the heat-sealable resin layer 4 to improve adhesion between these layers. As shown in Figure 4, a surface coating layer 6 may be provided on the outer side of the base layer 1 (the side opposite the heat-sealable resin layer 4) as needed.

The thickness of the laminate constituting the electrical storage device exterior material 10 is not particularly limited, but from the viewpoints of cost reduction, improved energy density, etc., it is preferably about 180 μm or less, about 155 μm or less, or about 120 μm or less. Furthermore, from the viewpoint of maintaining the function of the electrical storage device exterior material (10) of protecting the electrical storage device elements, the thickness of the laminate constituting the electrical storage device exterior material 10 is preferably about 35 μm or more, about 45 μm or more, or about 60 μm or more. Furthermore, preferred ranges for the laminate constituting the electrical storage device exterior material 10 include, for example, about 35 to 180 μm, about 35 to 155 μm, about 35 to 120 μm, about 45 to 180 μm, about 45 to 155 μm, about 45 to 120 μm, about 60 to 180 μm, about 60 to 155 μm, and about 60 to 120 μm, with about 60 to 155 μm being particularly preferred.

In the electrical storage device exterior material 10, the ratio of the total thickness of the base material layer 1, optional adhesive layer 2, barrier layer 3, optional adhesive layer 5, heat-sealable resin layer 4, and optional surface coating layer 6 to the thickness (total thickness) of the laminate constituting the electrical storage device exterior material 10 is preferably 90% or more, more preferably 95% or more, and even more preferably 98% or more. As a specific example, when the electrical storage device exterior material 10 of the present disclosure includes the base material layer 1, adhesive layer 2, barrier layer 3, adhesive layer 5, and heat-sealable resin layer 4, the ratio of the total thickness of these layers to the thickness (total thickness) of the laminate constituting the electrical storage device exterior material 10 is preferably 90% or more, more preferably 95% or more, and even more preferably 98% or more. Furthermore, even when the electrical storage device packaging material 10 of the present disclosure is a laminate including a substrate layer 1, an adhesive layer 2, a barrier layer 3, and a heat-sealable resin layer 4, the ratio of the total thickness of these layers to the thickness (total thickness) of the laminate constituting the electrical storage device packaging material 10 can be, for example, 80% or more, preferably 90% or more, more preferably 95% or more, and even more preferably 98% or more.

[Base material layer 1]
In the present disclosure, the substrate layer 1 is a layer provided for the purpose of allowing the packaging material for an electricity storage device to function as a substrate. The substrate layer 1 is located on the outer layer side of the packaging material for an electricity storage device.

There are no particular restrictions on the material from which the substrate layer 1 is made, as long as it functions as a substrate, i.e., has at least insulating properties. The substrate layer 1 can be made using, for example, a resin, which may contain additives as described below.

When the base layer 1 is formed from a resin, the base layer 1 may be, for example, a resin film formed from a resin, or may be formed by applying a resin. The resin film may be an unstretched film or a stretched film. Stretched films include uniaxially stretched films and biaxially stretched films, with biaxially stretched films being preferred. Stretching methods for forming biaxially stretched films include, for example, sequential biaxial stretching, inflation, and simultaneous biaxial stretching. Resin application methods include roll coating, gravure coating, and extrusion coating.

Examples of resins that form the base layer 1 include polyester, polyamide, polyolefin, epoxy resin, acrylic resin, fluororesin, polyurethane, silicone resin, and phenolic resin, as well as modified versions of these resins. The resin that forms the base layer 1 may also be a copolymer of these resins, or a modified version of the copolymer. It may also be a mixture of these resins.

Of these, polyester and polyamide are preferred as resins for forming the base layer 1.

Specific examples of polyesters include polyethylene terephthalate, polybutylene terephthalate, polyethylene naphthalate, polybutylene naphthalate, polyethylene isophthalate, and copolymer polyesters. Copolymer polyesters include those in which ethylene terephthalate is the main repeating unit. Specific examples include copolymer polyesters in which ethylene terephthalate is the main repeating unit polymerized with ethylene isophthalate (hereinafter abbreviated as polyethylene (terephthalate/isophthalate)), polyethylene (terephthalate/adipate), polyethylene (terephthalate/sodium sulfoisophthalate), polyethylene (terephthalate/sodium isophthalate), polyethylene (terephthalate/phenyl-dicarboxylate), and polyethylene (terephthalate/decanedicarboxylate). These polyesters may be used alone or in combination of two or more.

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

The substrate layer 1 preferably includes at least one of a polyester film, a polyamide film, and a polyolefin film, preferably at least one of a stretched polyester film, a stretched polyamide film, and a stretched polyolefin film, more preferably at least one of a stretched polyethylene terephthalate film, a stretched polybutylene terephthalate film, a stretched nylon film, and a stretched polypropylene film, and even more preferably at least one of a biaxially oriented polyethylene terephthalate film, a biaxially oriented polybutylene terephthalate film, a biaxially oriented nylon film, and a biaxially oriented polypropylene film.

The base layer 1 may be a single layer, or may be composed of two or more layers. When the base layer 1 is composed of two or more layers, the base layer 1 may be a laminate in which resin films are laminated with an adhesive or the like, or a laminate of resin films formed by co-extrusion of resins into two or more layers. Furthermore, a laminate of resin films formed by co-extrusion of resins into two or more layers may be used as the base layer 1 without being stretched, or may be uniaxially or biaxially stretched to form the base layer 1.

Specific examples of laminates of two or more resin films in the base layer 1 include a laminate of polyester film and nylon film, a laminate of two or more nylon film layers, and a laminate of two or more polyester film layers. Preferably, they are a laminate of stretched nylon film and stretched polyester film, a laminate of two or more stretched nylon film layers, or a laminate of two or more stretched polyester film layers. For example, when the base layer 1 is a laminate of two resin films, a laminate of polyester resin film and polyester resin film, a laminate of polyamide resin film and polyamide resin film, or a laminate of polyester resin film and polyamide resin film is preferred. A laminate of polyethylene terephthalate film and polyethylene terephthalate film, a laminate of nylon film and nylon film, or a laminate of polyethylene terephthalate film and nylon film is more preferred. Furthermore, because polyester resins are less likely to discolor when electrolyte solution adheres to their surface, it is preferable that the polyester resin film be the outermost layer of the base layer 1 when the base layer 1 is a laminate of two or more resin films.

When the substrate layer 1 is a laminate of two or more resin film layers, the two or more resin film layers may be laminated via an adhesive. Examples of preferred adhesives include those similar to those exemplified for adhesive layer 2, described below. The method for laminating two or more resin film layers is not particularly limited, and known methods can be used, such as dry lamination, sandwich lamination, extrusion lamination, and thermal lamination, with dry lamination being preferred. When laminating using the dry lamination method, a polyurethane adhesive is preferably used as the adhesive. In this case, the adhesive thickness can be, for example, approximately 2 to 5 μm. Alternatively, an anchor coat layer can be formed on the resin film before lamination. Examples of the anchor coat layer include those similar to those exemplified for adhesive layer 2, described below. In this case, the anchor coat layer thickness can be, for example, approximately 0.01 to 1.0 μm.

Additives such as lubricants, flame retardants, antiblocking agents, antioxidants, light stabilizers, tackifiers, and antistatic agents may also be present on at least one of the surface and interior of the base layer 1. A single type of additive may be used, or two or more types may be mixed together.

In the present disclosure, from the viewpoint of improving the formability of the exterior material for an electrical storage device, it is preferable that a lubricant be present on the surface of the base layer 1. The lubricant is not particularly limited, but preferably an amide-based lubricant is used. Specific examples of amide-based lubricants include saturated fatty acid amides, unsaturated fatty acid amides, substituted amides, methylolamides, saturated fatty acid bisamides, unsaturated fatty acid bisamides, fatty acid ester amides, and aromatic bisamides. Specific examples of saturated fatty acid amides include lauric acid amide, palmitic acid amide, stearic acid amide, behenic acid amide, and hydroxystearic acid amide. Specific examples of unsaturated fatty acid amides include oleic acid amide and erucic acid amide. Specific examples of substituted amides include N-oleyl palmitic acid amide, N-stearyl stearic acid amide, N-stearyl oleic acid amide, N-oleyl stearic acid amide, and N-stearyl erucic acid amide. Specific examples of methylolamides include methylol stearic acid amide. Specific examples of saturated fatty acid bisamides include methylene bisstearic acid amide, ethylene biscapric acid amide, ethylene bislauric acid amide, ethylene bisstearic acid amide, ethylene bishydroxystearic acid amide, ethylene bisbehenic acid amide, hexamethylene bisstearic acid amide, hexamethylene bisbehenic acid amide, hexamethylene hydroxystearic acid amide, N,N'-distearyl adipamide, N,N'-distearyl sebacic acid amide, etc. Specific examples of unsaturated fatty acid bisamides include ethylene bisoleic acid amide, ethylene biserucic acid amide, hexamethylene bisoleic acid amide, N,N'-dioleyl adipamide, N,N'-dioleyl sebacic acid amide, etc. Specific examples of fatty acid ester amides include stearamidoethyl stearate, etc. Specific examples of aromatic bisamides include m-xylylene bisstearic acid amide, m-xylylene bishydroxystearic acid amide, and N,N'-distearyl isophthalic acid amide. The lubricants may be used alone or in combination of two or more.

When a lubricant is present on the surface of the base layer 1, the amount thereof is not particularly limited, but is preferably about 3 mg/ ^m2 or more, more preferably about 4 to 15 mg/ ^m2 , and even more preferably about ⁵ to 14 mg/m2.

The lubricant present on the surface of the base layer 1 may be a lubricant exuded from the resin that makes up the base layer 1, or a lubricant applied to the surface of the base layer 1.

The thickness of the substrate layer 1 is not particularly limited as long as it functions as a substrate, but examples include approximately 3 to 50 μm, and preferably approximately 10 to 35 μm. When the substrate layer 1 is a laminate of two or more resin film layers, the thickness of each resin film constituting each layer is preferably approximately 2 to 25 μm.

[Adhesive layer 2]
In the packaging material for an electricity storage device of the present disclosure, the adhesive layer 2 is a layer that is provided between the base layer 1 and the barrier layer 3 as needed for the purpose of increasing the adhesion between them.

The adhesive layer 2 is formed from an adhesive capable of bonding the base layer 1 and the barrier layer 3. There are no limitations on the adhesive used to form the adhesive layer 2, and it may be any of a chemical reaction type, a solvent evaporation type, a hot melt type, a thermocompression type, etc. It may also be a two-component curing adhesive (two-component adhesive), a one-component curing adhesive (one-component adhesive), or a resin that does not involve a curing reaction. The adhesive layer 2 may be a single layer or multiple layers.

Specific examples of adhesive components include polyesters such as polyethylene terephthalate, polybutylene terephthalate, polyethylene naphthalate, polybutylene naphthalate, polyethylene isophthalate, and copolymer polyesters; polyethers; polyurethanes; epoxy resins; phenolic resins; polyamides such as nylon 6, nylon 66, nylon 12, and copolymer polyamides; polyolefin resins such as polyolefins, cyclic polyolefins, acid-modified polyolefins, and acid-modified cyclic polyolefins; polyvinyl acetate; cellulose; (meth)acrylic resins; polyimides; polycarbonates; amino resins such as urea resins and melamine resins; rubbers such as chloroprene rubber, nitrile rubber, and styrene-butadiene rubber; and silicone resins. These adhesive components may be used alone or in combination. Among these adhesive components, polyurethane adhesives are preferred. Furthermore, the adhesive strength of these adhesive resins can be increased by using an appropriate curing agent. The curing agent is selected from polyisocyanates, multifunctional epoxy resins, oxazoline group-containing polymers, polyamine resins, acid anhydrides, and other materials depending on the functional groups of the adhesive components.

Examples of polyurethane adhesives include those containing a base agent containing a polyol compound and a curing agent containing an isocyanate compound. Two-component curing polyurethane adhesives are preferred, with a polyol such as polyester polyol, polyether polyol, or acrylic polyol as the base agent and an aromatic or aliphatic polyisocyanate as the curing agent. Furthermore, it is preferable to use a polyester polyol that has hydroxyl groups on the side chain in addition to the terminal hydroxyl groups of the repeating unit as the polyol compound. Examples of curing agents include aliphatic, alicyclic, aromatic, and araliphatic isocyanate compounds. Examples of isocyanate compounds include hexamethylene diisocyanate (HDI), xylylene diisocyanate (XDI), isophorone diisocyanate (IPDI), hydrogenated XDI (H6XDI), hydrogenated MDI (H12MDI), tolylene diisocyanate (TDI), diphenylmethane diisocyanate (MDI), and naphthalene diisocyanate (NDI). Also included are polyfunctional isocyanate modifications of one or more of these diisocyanates. Multimers (e.g., trimers) can also be used as polyisocyanate compounds. Examples of such multimers include adducts, biurets, and nurates. Forming the adhesive layer 2 using a polyurethane adhesive provides the electrical storage device exterior material with excellent electrolyte resistance, preventing peeling of the base layer 1 even when electrolyte adheres to the side surfaces.

In addition, other components may be added to the adhesive layer 2 as long as they do not impair adhesion, and may contain colorants, thermoplastic elastomers, tackifiers, fillers (including particles), etc. By including a colorant in the adhesive layer 2, the exterior material for an electrical storage device can be colored. Known colorants such as pigments and dyes can be used as colorants. Furthermore, only one type of colorant may be used, or two or more types may be mixed together.

As described above, for example, if the electrical storage device exterior material 10 is colored (specifically, if at least one of the layers located closer to the base layer 1 than the barrier layer 3 of the electrical storage device exterior material 10 (e.g., the base layer 1, adhesive layer 2, colored layer, or surface coating layer 6, as described below) is colored, and a color different from that of the barrier layer 3 is visible when the electrical storage device exterior material 10 is observed from the base layer 1 side), whitening on the curved surface 11 or the like is likely to lead to the product being determined to be defective. The quality control method of the present disclosure is particularly effective when the external appearance of the electrical storage device exterior material 10 is a dark color such as black. Therefore, it is preferable that the adhesive layer 2 of the electrical storage device exterior material 10 is colored.

There are no particular restrictions on the type of pigment, so long as it does not impair the adhesive properties of the adhesive layer 2. Examples of organic pigments include azo-based, phthalocyanine-based, quinacridone-based, anthraquinone-based, dioxazine-based, indigothioindigo-based, perinone-perylene-based, isoindolenine-based, and benzimidazolone-based pigments. Examples of inorganic pigments include carbon black-based, titanium oxide-based, cadmium-based, lead-based, chromium oxide-based, and iron-based pigments. Other examples include finely powdered mica and fish scale foil.

Among colorants, carbon black is preferred, for example, to give the exterior material for an electrical storage device a black appearance.

The average particle size of the pigment is not particularly limited, but may be, for example, approximately 0.05 to 5 μm, and preferably approximately 0.08 to 2 μm. The average particle size of the pigment is the median diameter measured using a laser diffraction/scattering particle size distribution analyzer.

The pigment content in the adhesive layer 2 is not particularly limited as long as it colors the electrical storage device exterior material, but may be, for example, approximately 5 to 60% by mass, and preferably 10 to 40% by mass.

The thickness of the adhesive layer 2 is not particularly limited as long as it can bond the base layer 1 and the barrier layer 3, but is, for example, approximately 1 μm or more, approximately 2 μm or more. The thickness of the adhesive layer 2 is, for example, approximately 10 μm or less, approximately 5 μm or less. Preferred thickness ranges for the adhesive layer 2 include approximately 1 to 10 μm, approximately 1 to 5 μm, approximately 2 to 10 μm, and approximately 2 to 5 μm.

[Colored layer]
The colored layer is a layer that is provided between the base material layer 1 and the barrier layer 3 as needed (not shown). When the adhesive layer 2 is provided, a colored layer may be provided between the base material layer 1 and the adhesive layer 2, or between the adhesive layer 2 and the barrier layer 3. A colored layer may also be provided on the outside of the base material layer 1. By providing a colored layer, the packaging material for an electricity storage device can be colored. A colored adhesive layer 2 and a colored layer may be provided between the base material layer 1 and the barrier layer 3.

The colored layer can be formed, for example, by applying ink containing a colorant to the surface of the base layer 1 or the surface of the barrier layer 3. Known colorants such as pigments and dyes can be used as colorants. Furthermore, a single type of colorant may be used, or two or more types may be mixed together.

Specific examples of colorants contained in the colored layer include the same as those exemplified in the [Adhesive Layer 2] section.

[Barrier layer 3]
In the packaging material for an electricity storage device, the barrier layer 3 is a layer that at least prevents the penetration of moisture.

Examples of the barrier layer 3 include metal foils, vapor-deposited films, and resin layers with barrier properties. Vapor-deposited films include metal vapor-deposited films, inorganic oxide vapor-deposited films, and carbon-containing inorganic oxide vapor-deposited films. Resin layers include fluorine-containing resins such as polyvinylidene chloride, polymers based on chlorotrifluoroethylene (CTFE), polymers based on tetrafluoroethylene (TFE), polymers containing fluoroalkyl groups, and polymers based on fluoroalkyl units, as well as ethylene-vinyl alcohol copolymers. Examples of the barrier layer 3 also include resin films comprising at least one of these vapor-deposited films and resin layers. The barrier layer 3 may comprise multiple layers. The barrier layer 3 preferably includes a layer composed of a metal material. Specific examples of metal materials that make up the barrier layer 3 include aluminum alloys, stainless steel, titanium steel, and steel plates. When used as a metal foil, the barrier layer 3 preferably includes at least one of aluminum alloy foil and stainless steel foil.

From the viewpoint of improving the formability of the electrical storage device exterior material, the aluminum alloy foil is preferably a soft aluminum alloy foil made of, for example, an annealed aluminum alloy, and from the viewpoint of further improving formability, it is preferably an iron-containing aluminum alloy foil. In the iron-containing aluminum alloy foil (100% by mass), the iron content is preferably 0.1 to 9.0% by mass, and more preferably 0.5 to 2.0% by mass. By having an iron content of 0.1% by mass or more, an electrical storage device exterior material with better formability can be obtained. By having an iron content of 9.0% by mass or less, an electrical storage device exterior material with better flexibility can be obtained. Examples of soft aluminum alloy foils include aluminum alloy foils having compositions specified in JIS H4160:1994 A8021H-O, JIS H4160:1994 A8079H-O, JIS H4000:2014 A8021P-O, or JIS H4000:2014 A8079P-O. Silicon, magnesium, copper, manganese, etc. may also be added as needed. Softening can be achieved by annealing or other methods.

Furthermore, examples of stainless steel foil include austenitic, ferritic, austenitic-ferritic, martensitic, and precipitation-hardened stainless steel foils. Furthermore, from the perspective of providing an exterior material for an electricity storage device with excellent formability, it is preferable that the stainless steel foil be made of austenitic stainless steel.

Specific examples of austenitic stainless steels that make up the stainless steel foil include SUS304, SUS301, and SUS316L, with SUS301 and SUS304 being particularly preferred.

In the case of a metal foil, the thickness of the barrier layer 3 should at least function as a barrier layer to prevent moisture penetration, and may be, for example, approximately 9 to 200 μm. The thickness of the barrier layer 3 is preferably approximately 85 μm or less, more preferably approximately 50 μm or less, even more preferably approximately 40 μm or less, and particularly preferably approximately 35 μm or less. The thickness of the barrier layer 3 is preferably approximately 10 μm or more, even more preferably approximately 20 μm or more, and more preferably approximately 25 μm or more. Preferred thickness ranges for the barrier layer 3 include approximately 10 to 85 μm, approximately 10 to 50 μm, approximately 10 to 40 μm, approximately 10 to 35 μm, approximately 20 to 85 μm, approximately 20 to 50 μm, approximately 20 to 40 μm, approximately 20 to 35 μm, approximately 25 to 85 μm, approximately 25 to 50 μm, approximately 25 to 40 μm, and approximately 25 to 35 μm. When the barrier layer 3 is made of aluminum alloy foil, the above-mentioned range is particularly preferred. Furthermore, when the barrier layer 3 is made of stainless steel foil, the thickness of the stainless steel foil is preferably about 60 μm or less, more preferably about 50 μm or less, even more preferably about 40 μm or less, even more preferably about 30 μm or less, and particularly preferably about 25 μm or less. The thickness of the stainless steel foil is preferably about 10 μm or more, more preferably about 15 μm or more. Preferred thickness ranges for the stainless steel foil include approximately 10 to 60 μm, approximately 10 to 50 μm, approximately 10 to 40 μm, approximately 10 to 30 μm, approximately 10 to 25 μm, approximately 15 to 60 μm, approximately 15 to 50 μm, approximately 15 to 40 μm, approximately 15 to 30 μm, and approximately 15 to 25 μm.

Furthermore, when the barrier layer 3 is a metal foil, it is preferable that at least the surface opposite the substrate layer be provided with a corrosion-resistant coating to prevent dissolution and corrosion. The barrier layer 3 may be provided with a corrosion-resistant coating on both sides. Here, a corrosion-resistant coating refers to a thin film formed on the surface of the barrier layer that is corrosion-resistant, and is obtained by, for example, hydrothermal conversion treatment such as boehmite treatment, chemical conversion treatment, anodizing treatment, plating treatment with nickel or chromium, or corrosion prevention treatment such as applying a coating agent. A single type of treatment may be used to form the corrosion-resistant coating, or two or more types may be combined. Furthermore, multiple layers may be formed, rather than a single layer. Furthermore, among these treatments, hydrothermal conversion treatment and anodizing treatment dissolve the metal foil surface with a treatment agent to form a metal compound with excellent corrosion resistance. Note that these treatments may also be included in the definition of chemical conversion treatment. Furthermore, when the barrier layer 3 has a corrosion-resistant coating, the corrosion-resistant coating is also included in the barrier layer 3.

The corrosion-resistant coating prevents delamination between the barrier layer (e.g., aluminum alloy foil) and the substrate layer during molding of the electrical storage device exterior material, prevents dissolution and corrosion of the barrier layer surface due to hydrogen fluoride produced by the reaction between the electrolyte and water, and particularly prevents dissolution and corrosion of aluminum oxide present on the barrier layer surface when the barrier layer is aluminum alloy foil, and also improves the adhesion (wettability) of the barrier layer surface, preventing delamination between the substrate layer and barrier layer during heat sealing and molding.

Various corrosion-resistant coatings formed by chemical conversion treatments are known, including those containing at least one of phosphates, chromates, fluorides, triazine thiol compounds, and rare earth oxides. Examples of chemical conversion treatments using phosphates and chromates include chromate chromate treatment, phosphate chromate treatment, phosphate-chromate treatment, and chromate treatment. Chromium compounds used in these treatments include chromium nitrate, chromium fluoride, chromium sulfate, chromium acetate, chromium oxalate, chromium biphosphate, chromate acetylacetate, chromium chloride, and potassium chromium sulfate. Phosphorus compounds used in these treatments include sodium phosphate, potassium phosphate, ammonium phosphate, and polyphosphoric acid. Chromate treatments include etching chromate treatment, electrolytic chromate treatment, and paint-on chromate treatment, with paint-on chromate treatment being preferred. This paint-type chromate treatment involves first degreasing at least the inner surface of a barrier layer (e.g., an aluminum alloy foil) using a well-known method such as alkali immersion, electrolytic cleaning, acid pickling, electrolytic pickling, or acid activation, and then coating the degreased surface with a treatment solution containing, as its main component, a metal phosphate such as chromium (Cr) phosphate, titanium (Ti) phosphate, zirconium (Zr) phosphate, or zinc (Zn) phosphate, or a mixture of these metal salts, or a treatment solution containing, as its main component, a nonmetallic phosphate and a mixture of these nonmetallic salts, or a mixture of these with a synthetic resin, by a well-known coating method such as roll coating, gravure printing, or immersion, followed by drying. The treatment solution can be, for example, water, alcoholic solvents, hydrocarbon solvents, ketone solvents, ester solvents, or ether solvents, with water being preferred. The resin component used here may include polymers such as phenolic resins and acrylic resins, and examples thereof include chromate treatment using an aminated phenolic polymer having repeating units represented by the following general formulas (1) to (4). The aminated phenolic polymer may contain one repeating unit represented by the following general formulas (1) to (4) alone, or any combination of two or more repeating units. The acrylic resin is preferably polyacrylic acid, an acrylic acid-methacrylic acid ester copolymer, an acrylic acid-maleic acid copolymer, an acrylic acid-styrene copolymer, or a derivative thereof, such as a sodium salt, an ammonium salt, or an amine salt. Derivatives of polyacrylic acid, such as the ammonium salt, sodium salt, or amine salt of polyacrylic acid, are particularly preferred. In this disclosure, polyacrylic acid refers to a polymer of acrylic acid. The acrylic resin is also preferably a copolymer of acrylic acid and a dicarboxylic acid or a dicarboxylic acid anhydride, and preferably an ammonium salt, a sodium salt, or an amine salt of a copolymer of acrylic acid and a dicarboxylic acid or a dicarboxylic acid anhydride. Only one type of acrylic resin may be used, or two or more types may be mixed together.

In general formulas (1) to (4), X represents a hydrogen atom, a hydroxy group, an alkyl group, a hydroxyalkyl group, an allyl group, or a benzyl group. ^R1 and ^R2 , which may be the same or different, represent a hydroxy group, an alkyl group, or a hydroxyalkyl group. In general formulas (1) to (4), examples of the alkyl group represented by X, ^R1 , and ^R2 include linear or branched alkyl groups having 1 to 4 carbon atoms, such as a methyl group, an ethyl group, an n-propyl group, an isopropyl group, an n-butyl group, an isobutyl group, and a tert-butyl group. Examples of the hydroxyalkyl group represented by X, ^R1 , and ^R2 include linear or branched alkyl groups having 1 to 4 carbon atoms and substituted with one hydroxy group, such as a hydroxymethyl group, a 1-hydroxyethyl group, a 2-hydroxyethyl group, a 1-hydroxypropyl group, a 2-hydroxypropyl group, a 3-hydroxypropyl group, a 1-hydroxybutyl group, a 2-hydroxybutyl group, a 3-hydroxybutyl group, and a 4-hydroxybutyl group. In general formulas (1) to (4), the alkyl groups and hydroxyalkyl groups represented by X, ^R1 , and ^R2 may be the same or different. In general formulas (1) to (4), X is preferably a hydrogen atom, a hydroxy group, or a hydroxyalkyl group. The number-average molecular weight of the aminated phenol polymer having repeating units represented by general formulas (1) to (4) is preferably, for example, about 500 to 1,000,000, and more preferably about 1,000 to 20,000. The aminated phenol polymer can be produced, for example, by polycondensing a phenol compound or a naphthol compound with formaldehyde to produce a polymer comprising repeating units represented by general formula ( ₁ ) or ^{(3), and then introducing a functional group (—CH2NR1R2) into the resulting polymer using formaldehyde and an amine (R1R2NH ) . The} aminated phenol polymer may be used alone or in combination of two or more types.

Other examples of corrosion-resistant coatings include thin films formed by a coating-type corrosion prevention treatment in which a coating agent containing at least one selected from the group consisting of rare earth element oxide sol, anionic polymer, and cationic polymer is applied. The coating agent may further contain phosphoric acid or phosphate salts, and a crosslinking agent for crosslinking the polymer. The rare earth element oxide sol contains rare earth element oxide fine particles (e.g., particles with an average particle size of 100 nm or less) dispersed in a liquid dispersion medium. Examples of rare earth element oxides include cerium oxide, yttrium oxide, neodymium oxide, and lanthanum oxide, with cerium oxide being preferred for improved adhesion. The rare earth element oxides contained in the corrosion-resistant coating can be used alone or in combination of two or more. Liquid dispersion media for the rare earth element oxide sol can include various solvents, such as water, alcohol-based solvents, hydrocarbon-based solvents, ketone-based solvents, ester-based solvents, and ether-based solvents, with water being preferred. Preferred examples of cationic polymers include polyethyleneimine, ionic polymer complexes consisting of polyethyleneimine and a polymer having a carboxylic acid, primary amine-grafted acrylic resins in which a primary amine is graft-polymerized onto an acrylic backbone, polyallylamine or its derivatives, and aminated phenols. Preferred anionic polymers are poly(meth)acrylic acid or its salts, or copolymers primarily composed of (meth)acrylic acid or its salts. The crosslinking agent is preferably at least one selected from the group consisting of compounds having a functional group selected from isocyanate, glycidyl, carboxyl, and oxazoline groups, and silane coupling agents. The phosphoric acid or phosphoric acid salt is preferably condensed phosphoric acid or a condensed phosphate salt.

One example of a corrosion-resistant coating is one formed by applying a solution of fine particles of metal oxides such as aluminum oxide, titanium oxide, cerium oxide, and tin oxide, or barium sulfate dispersed in phosphoric acid to the surface of the barrier layer and then baking it at 150°C or higher.

If necessary, the corrosion-resistant coating may have a laminated structure in which at least one of a cationic polymer and an anionic polymer is further laminated. Examples of cationic polymers and anionic polymers include those described above.

The composition of the corrosion-resistant coating can be analyzed using, for example, time-of-flight secondary ion mass spectrometry.

The amount of the corrosion-resistant coating formed on the surface of the barrier layer 3 in the chemical conversion treatment is not particularly limited. For example, in the case of a paint-type chromate treatment, it is desirable that the barrier layer 3 contain, ^per square meter of its surface, about 0.5 to 50 mg, preferably about 1.0 to 40 mg, of a chromium-equivalent chromate compound, about 0.5 to 50 mg, preferably about 1.0 to 40 mg, of a phosphorus compound, and about 1.0 to 200 mg, preferably about 5.0 to 150 mg, of an aminated phenol polymer, in phosphorus-equivalent amounts.

The thickness of the corrosion-resistant coating is not particularly limited, but is preferably about 1 nm to 20 μm, more preferably about 1 nm to 100 nm, and even more preferably about 1 nm to 50 nm, from the viewpoint of the cohesive strength of the coating and the adhesion strength with the barrier layer and the thermally adhesive resin layer. The thickness of the corrosion-resistant coating can be measured by observation with a transmission electron microscope, or by a combination of observation with a transmission electron microscope and energy dispersive X-ray spectroscopy or electron energy loss spectroscopy. Analysis of the composition of the corrosion-resistant coating using time-of-flight secondary ion mass spectrometry detects peaks derived from, for example, secondary ions composed of Ce, P, and O (e.g., at least one of Ce ₂ PO ₄ ⁺ and CePO ₄ ⁻ ) or secondary ions composed of Cr, P, and O (e.g., at least one of CrPO ₂ ⁺ and CrPO ₄ ⁻ ).

Chemical conversion treatment is performed by applying a solution containing the compound used to form the corrosion-resistant coating to the surface of the barrier layer using methods such as bar coating, roll coating, gravure coating, or immersion, and then heating the barrier layer to a temperature of approximately 70 to 200°C. Furthermore, before applying chemical conversion treatment to the barrier layer, the barrier layer may be subjected to a degreasing treatment using methods such as alkaline immersion, electrolytic cleaning, acid cleaning, or electrolytic acid cleaning. Performing such a degreasing treatment allows for more efficient chemical conversion treatment of the barrier layer surface. Furthermore, using an acid degreasing agent in which a fluorine-containing compound is dissolved in an inorganic acid not only degreases the metal foil but also forms a passive metal fluoride. In such cases, it is possible to perform only the degreasing treatment.

[Thermofusible resin layer 4]
In the exterior packaging material for an electricity storage device of the present disclosure, the heat-sealable resin layer 4 corresponds to the innermost layer and is a layer (sealant layer) that functions to seal the electricity storage device elements by heat-sealing the heat-sealable resin layers to each other when assembling the electricity storage device.

The resin constituting the heat-sealable resin layer 4 is not particularly limited as long as it is heat-sealable, but resins containing a polyolefin skeleton, such as polyolefins and acid-modified polyolefins, are preferred. The polyolefin skeleton of the resin constituting the heat-sealable resin layer 4 can be determined by, for example, infrared spectroscopy or gas chromatography-mass spectrometry. Furthermore, when the resin constituting the heat-sealable resin layer 4 is analyzed by infrared spectroscopy, peaks derived from maleic anhydride are preferably detected. For example, when measuring maleic anhydride-modified polyolefin by infrared spectroscopy, peaks derived from maleic anhydride are detected near wavenumbers 1760 cm ⁻¹ and 1780 cm ⁻¹ . When the heat-sealable resin layer 4 is a layer composed of maleic anhydride-modified polyolefin, peaks derived from maleic anhydride are detected by infrared spectroscopy. However, if the degree of acid modification is low, the peaks may be small and not be detected. In such cases, analysis can be performed by nuclear magnetic resonance spectroscopy.

Specific examples of polyolefins include polyethylenes such as low-density polyethylene, medium-density polyethylene, high-density polyethylene, and linear low-density polyethylene; ethylene-α-olefin copolymers; polypropylenes such as homopolypropylene, block copolymers of polypropylene (e.g., block copolymers of propylene and ethylene), and random copolymers of polypropylene (e.g., random copolymers of propylene and ethylene); propylene-α-olefin copolymers; and ethylene-butene-propylene terpolymers. Of these, polypropylene is preferred. When the polyolefin resin is a copolymer, it may be a block copolymer or a random copolymer. These polyolefin resins may be used alone or in combination of two or more.

The polyolefin may also be a cyclic polyolefin. Cyclic polyolefins are copolymers of olefins and cyclic monomers. Examples of olefins that constitute the cyclic polyolefin include ethylene, propylene, 4-methyl-1-pentene, styrene, butadiene, and isoprene. Examples of cyclic monomers that constitute the cyclic polyolefin include cyclic alkenes such as norbornene; and cyclic dienes such as cyclopentadiene, dicyclopentadiene, cyclohexadiene, and norbornadiene. Among these, cyclic alkenes are preferred, and norbornene is even more preferred.

Acid-modified polyolefins are polymers modified by block or graft polymerization of polyolefins with an acid component. Examples of acid-modified polyolefins include the polyolefins listed above, copolymers of the polyolefins with polar molecules such as acrylic acid or methacrylic acid, and cross-linked polyolefins. Examples of acid components used for acid modification include carboxylic acids or anhydrides such as maleic acid, acrylic acid, itaconic acid, crotonic acid, maleic anhydride, and itaconic anhydride.

The acid-modified polyolefin may be an acid-modified cyclic polyolefin. An acid-modified cyclic polyolefin is a polymer obtained by copolymerizing a portion of the monomers constituting the cyclic polyolefin with an acid component, or by block or graft polymerizing an acid component onto a cyclic polyolefin. The acid-modified cyclic polyolefin is the same as described above. The acid component used for the acid modification is the same as the acid component used to modify the polyolefin described above.

Preferred acid-modified polyolefins include polyolefins modified with carboxylic acids or their anhydrides, polypropylenes modified with carboxylic acids or their anhydrides, maleic anhydride-modified polyolefins, and maleic anhydride-modified polypropylenes.

The heat-sealable resin layer 4 may be formed from a single type of resin, or may be formed from a blend polymer of two or more types of resin. Furthermore, the heat-sealable resin layer 4 may be formed from only one layer, or may be formed from two or more layers of the same or different resins.

The heat-sealable resin layer 4 may also contain a lubricant, if necessary. When the heat-sealable resin layer 4 contains a lubricant, the formability of the electrical storage device packaging material can be improved. There are no particular restrictions on the lubricant, and any known lubricant can be used. The lubricant may be used alone or in combination of two or more types.

The lubricant is not particularly limited, but preferably an amide-based lubricant is used. Specific examples of lubricants include those exemplified for base layer 1. One type of lubricant may be used alone, or two or more types may be used in combination.

When a lubricant is present on the surface of the heat-fusible resin layer 4, the amount thereof is not particularly limited, but from the viewpoint of improving the formability of the exterior material for an electricity storage device, it is preferably about 10 to 50 mg/ ^m2 , and more preferably about 15 to 40 mg/ ^m2 .

The lubricant present on the surface of the heat-sealable resin layer 4 may be a lubricant exuded from the resin that makes up the heat-sealable resin layer 4, or a lubricant applied to the surface of the heat-sealable resin layer 4.

The thickness of the heat-sealable resin layer 4 is not particularly limited as long as it functions to heat-seal the heat-sealable resin layers together and seal the electricity storage device element, but examples include approximately 100 μm or less, preferably approximately 85 μm or less, and more preferably approximately 15 to 85 μm. For example, if the thickness of the adhesive layer 5 described below is 10 μm or greater, the thickness of the heat-sealable resin layer 4 is preferably approximately 85 μm or less, more preferably approximately 15 to 45 μm. For example, if the thickness of the adhesive layer 5 described below is less than 10 μm or if the adhesive layer 5 is not provided, the thickness of the heat-sealable resin layer 4 is preferably approximately 20 μm or greater, more preferably approximately 35 to 85 μm.

[Adhesive layer 5]
In the packaging material for an electricity storage device of the present disclosure, the adhesive layer 5 is a layer that is provided as needed between the barrier layer 3 (or the corrosion-resistant coating) and the heat-sealable resin layer 4 in order to firmly bond them together.

The adhesive layer 5 is formed from a resin capable of bonding the barrier layer 3 and the heat-sealable resin layer 4. Examples of resins that can be used to form the adhesive layer 5 include the same adhesives as those exemplified for the adhesive layer 2. Furthermore, from the perspective of firmly bonding the adhesive layer 5 and the heat-sealable resin layer 4, the resin used to form the adhesive layer 5 preferably contains a polyolefin skeleton, such as the polyolefins and acid-modified polyolefins exemplified for the heat-sealable resin layer 4. On the other hand, from the perspective of firmly bonding the barrier layer 3 and the adhesive layer 5, the adhesive layer 5 preferably contains an acid-modified polyolefin. Examples of acid-modified components include dicarboxylic acids such as maleic acid, itaconic acid, succinic acid, and adipic acid, as well as their anhydrides, acrylic acid, and methacrylic acid. However, maleic anhydride is most preferred in terms of ease of modification and versatility. Furthermore, from the perspective of the heat resistance of the electrical storage device packaging material, the olefin component is preferably a polypropylene-based resin, and the adhesive layer 5 most preferably contains maleic anhydride-modified polypropylene.

The inclusion of a polyolefin skeleton in the resin constituting the adhesive layer 5 can be determined by, for example, infrared spectroscopy, gas chromatography mass spectrometry, or the like; the analysis method is not particularly limited. Furthermore, the inclusion of an acid-modified polyolefin in the resin constituting the adhesive layer 5 can be determined, for example, by measuring a maleic anhydride-modified polyolefin by infrared spectroscopy, whereby peaks derived from maleic anhydride are detected at wavenumbers of approximately 1760 ^cm and 1780 ^cm . However, if the degree of acid modification is low, the peaks may be small and not be detected. In such cases, analysis can be performed by nuclear magnetic resonance spectroscopy.

Furthermore, from the perspective of ensuring durability, such as heat resistance and resistance to contents, of the electrical storage device exterior packaging material, and ensuring formability while reducing the thickness, it is more preferable that the adhesive layer 5 be a cured product of a resin composition containing an acid-modified polyolefin and a curing agent. Preferred examples of acid-modified polyolefins include those listed above.

The adhesive layer 5 is preferably a cured product of a resin composition containing an acid-modified polyolefin and at least one compound selected from the group consisting of a compound having an isocyanate group, a compound having an oxazoline group, and a compound having an epoxy group. It is particularly preferably a cured product of a resin composition containing an acid-modified polyolefin and at least one compound selected from the group consisting of a compound having an isocyanate group and a compound having an epoxy group. The adhesive layer 5 also preferably contains at least one compound selected from the group consisting of polyurethane, polyester, and epoxy resin, and more preferably polyurethane and epoxy resin. Preferred polyesters include, for example, ester resins formed by the reaction of epoxy groups with maleic anhydride groups, and amide ester resins formed by the reaction of oxazoline groups with maleic anhydride groups. If unreacted curing agents such as compounds having an isocyanate group, compounds having an oxazoline group, or epoxy resins remain in the adhesive layer 5, the presence of the unreacted materials can be confirmed by a method selected from the group consisting of infrared spectroscopy, Raman spectroscopy, time-of-flight secondary ion mass spectrometry (TOF-SIMS), etc.

In order to further enhance the adhesion between the barrier layer 3 and the adhesive layer 5, the adhesive layer 5 is preferably a cured product of a resin composition containing a curing agent having at least one selected from the group consisting of an oxygen atom, a heterocycle, a C=N bond, and a C-O-C bond. Examples of curing agents having a heterocycle include curing agents having an oxazoline group and curing agents having an epoxy group. Examples of curing agents having a C=N bond include curing agents having an oxazoline group and curing agents having an isocyanate group. Examples of curing agents having a C-O-C bond include curing agents having an oxazoline group and curing agents having an epoxy group. Whether the adhesive layer 5 is a cured product of a resin composition containing such a curing agent can be confirmed by, for example, gas chromatography mass spectrometry (GCMS), infrared spectroscopy (IR), time-of-flight secondary ion mass spectrometry (TOF-SIMS), X-ray photoelectron spectroscopy (XPS), or other methods.

The compound having an isocyanate group is not particularly limited, but from the viewpoint of effectively enhancing adhesion between the barrier layer 3 and the adhesive layer 5, a polyfunctional isocyanate compound is preferable. The polyfunctional isocyanate compound is not particularly limited as long as it has two or more isocyanate groups. Specific examples of polyfunctional isocyanate curing agents include pentane diisocyanate (PDI), isophorone diisocyanate (IPDI), hexamethylene diisocyanate (HDI), tolylene diisocyanate (TDI), diphenylmethane diisocyanate (MDI), polymers or nurates thereof, mixtures of these, and copolymers with other polymers. Other examples include adducts, biuret compounds, and isocyanurates.

The content of the compound having an isocyanate group in the adhesive layer 5 is preferably in the range of 0.1 to 50% by mass, and more preferably in the range of 0.5 to 40% by mass, of the resin composition that constitutes the adhesive layer 5. This effectively improves the adhesion between the barrier layer 3 and the adhesive layer 5.

The compound having an oxazoline group is not particularly limited as long as it has an oxazoline skeleton. Specific examples of compounds having an oxazoline group include those having a polystyrene main chain and those having an acrylic main chain. Commercially available products include the Epocross series manufactured by Nippon Shokubai Co., Ltd.

The proportion of the compound having an oxazoline group in the adhesive layer 5 is preferably in the range of 0.1 to 50 mass %, and more preferably in the range of 0.5 to 40 mass %, of the resin composition that constitutes the adhesive layer 5. This effectively improves the adhesion between the barrier layer 3 and the adhesive layer 5.

An example of a compound having an epoxy group is an epoxy resin. There are no particular restrictions on the epoxy resin, so long as it is a resin capable of forming a crosslinked structure via the epoxy groups present in the molecule, and known epoxy resins can be used. The weight-average molecular weight of the epoxy resin is preferably approximately 50 to 2,000, more preferably approximately 100 to 1,000, and even more preferably approximately 200 to 800. In the first disclosure, the weight-average molecular weight of the epoxy resin is a value measured by gel permeation chromatography (GPC) under conditions using polystyrene as a standard sample.

Specific examples of epoxy resins include glycidyl ether derivatives of trimethylolpropane, bisphenol A diglycidyl ether, modified bisphenol A diglycidyl ether, bisphenol F glycidyl ether, novolac glycidyl ether, glycerin polyglycidyl ether, and polyglycerin polyglycidyl ether. Epoxy resins may be used alone or in combination of two or more.

The proportion of epoxy resin in adhesive layer 5 is preferably in the range of 0.1 to 50% by mass, and more preferably in the range of 0.5 to 40% by mass, of the resin composition that makes up adhesive layer 5. This effectively improves the adhesion between barrier layer 3 and adhesive layer 5.

The polyurethane is not particularly limited, and any known polyurethane can be used. The adhesive layer 5 may be, for example, a cured product of a two-component curing polyurethane.

The proportion of polyurethane in adhesive layer 5 is preferably in the range of 0.1 to 50 mass % of the resin composition constituting adhesive layer 5, and more preferably in the range of 0.5 to 40 mass %. This effectively improves adhesion between barrier layer 3 and adhesive layer 5 in an atmosphere containing components that induce corrosion of the barrier layer, such as electrolyte solution.

When adhesive layer 5 is a cured product of a resin composition containing at least one selected from the group consisting of a compound having an isocyanate group, a compound having an oxazoline group, and an epoxy resin, and the acid-modified polyolefin, the acid-modified polyolefin functions as the base resin, and the compound having an isocyanate group, the compound having an oxazoline group, and the compound having an epoxy group each function as a curing agent.

The adhesive layer 5 may contain a modifier having a carbodiimide group.

The thickness of adhesive layer 5 is preferably approximately 50 μm or less, approximately 40 μm or less, approximately 30 μm or less, approximately 20 μm or less, or approximately 5 μm or less. Furthermore, the thickness of adhesive layer 5 is preferably approximately 0.1 μm or more, or approximately 0.5 μm or more. Furthermore, the thickness range of adhesive layer 5 is preferably approximately 0.1 to 50 μm, approximately 0.1 to 40 μm, approximately 0.1 to 30 μm, approximately 0.1 to 20 μm, approximately 0.1 to 5 μm, approximately 0.5 to 50 μm, approximately 0.5 to 40 μm, approximately 0.5 to 30 μm, approximately 0.5 to 20 μm, or approximately 0.5 to 5 μm. More specifically, for adhesives such as those exemplified for adhesive layer 2 or a cured product of an acid-modified polyolefin and a curing agent, the thickness is preferably approximately 1 to 10 μm, more preferably approximately 1 to 5 μm. Furthermore, when using a resin exemplified for the heat-sealable resin layer 4, the thickness is preferably about 2 to 50 μm, and more preferably about 10 to 40 μm. When the adhesive layer 5 is an adhesive exemplified for the adhesive layer 2, or a cured product of a resin composition containing an acid-modified polyolefin and a curing agent, the adhesive layer 5 can be formed, for example, by applying the resin composition and curing it by heating or the like. When using a resin exemplified for the heat-sealable resin layer 4, the heat-sealable resin layer 4 and the adhesive layer 5 can be formed, for example, by extrusion molding.

[Surface coating layer 6]
The packaging material for an electricity storage device according to the present disclosure may, if necessary, have a surface coating layer 6 on the substrate layer 1 (the side of the substrate layer 1 opposite to the barrier layer 3) for the purpose of improving at least one of design, electrolyte resistance, scratch resistance, formability, etc. The surface coating layer 6 is a layer located on the outermost layer side of the packaging material for an electricity storage device when an electricity storage device is assembled using the packaging material for an electricity storage device.

The surface coating layer 6 can be formed from at least one of the following resins: polyvinylidene chloride, polyester, polyurethane, acrylic resin, epoxy resin, polyamide, fluororesin, silicone resin, phenolic resin, etc.; mixtures of these resins; modified versions of these resins; copolymers containing these resins; and copolymers containing modified versions of these resins. The resin is preferably a curable resin.

When the resin forming the surface coating layer 6 is a curable resin, the resin may be either a one-component curable resin or a two-component curable resin, but is preferably a two-component curable resin. Examples of two-component curable resins include two-component curable polyurethane, two-component curable polyester, and two-component curable epoxy resin. Of these, two-component curable polyurethane is preferred.

Examples of two-component curing polyurethanes include polyurethanes containing a polyol compound as a base component and an isocyanate compound as a curing agent. Preferred examples include two-component curing polyurethanes that use a polyol, such as polyester polyol, polyether polyol, or acrylic polyol, as the base component and an aromatic or aliphatic polyisocyanate as the curing agent. In particular, it is preferable for the polyol to contain two or more of polyester polyol, polyether polyol, or acrylic polyol, and it is even more preferable for the polyol to contain two or more of polyester polyol, polyether polyol, and acrylic polyol. Furthermore, it is preferable for the polyol to contain an acrylic polyol. It is preferable for the curing agent to contain an aromatic isocyanate compound. It is also preferable for the polyol compound to be a polyester polyol that has hydroxyl groups on the side chain in addition to the terminal hydroxyl groups of the repeating unit. Examples of curing agents include aliphatic, alicyclic, aromatic, and araliphatic isocyanate compounds. Examples of isocyanate compounds include hexamethylene diisocyanate (HDI), xylylene diisocyanate (XDI), isophorone diisocyanate (IPDI), hydrogenated XDI (H6XDI), hydrogenated MDI (H12MDI), tolylene diisocyanate (TDI), diphenylmethane diisocyanate (MDI), and naphthalene diisocyanate (NDI). Also included are polyfunctional isocyanate-modified compounds of one or more of these diisocyanates. Furthermore, polymers (e.g., trimers) can also be used as polyisocyanate compounds. Examples of such polymers include adducts, biurets, and nurates. Note that an aliphatic isocyanate compound refers to an isocyanate that has an aliphatic group but no aromatic ring, an alicyclic isocyanate compound refers to an isocyanate that has an alicyclic hydrocarbon group, and an aromatic isocyanate compound refers to an isocyanate that has an aromatic ring. Forming the surface coating layer 6 from polyurethane provides the electrical storage device exterior material with excellent electrolyte resistance.

The surface coating layer 6 may contain additives such as the aforementioned lubricants, antiblocking agents, matting agents (fillers (particles, etc.)), flame retardants, antioxidants, tackifiers, and antistatic agents, at least on the surface and/or inside of the surface coating layer 6, as needed, depending on the functionality to be provided by the surface coating layer 6 and its surface. Examples of additives include fine particles with an average particle size of approximately 0.5 nm to 5 μm. The average particle size of the additive is the median size measured using a laser diffraction/scattering particle size distribution analyzer.

Additives may be either inorganic or organic. There are also no particular restrictions on the shape of the additive, and examples include spherical, fibrous, plate-like, irregular, and scaly shapes.

Specific examples of additives include talc, silica, graphite, kaolin, montmorillonite, mica, hydrotalcite, silica gel, zeolite, aluminum hydroxide, magnesium hydroxide, zinc oxide, magnesium oxide, aluminum oxide, neodymium oxide, antimony oxide, titanium oxide, cerium oxide, calcium sulfate, barium sulfate, calcium carbonate, calcium silicate, lithium carbonate, calcium benzoate, calcium oxalate, magnesium stearate, alumina, carbon black, carbon nanotubes, high-melting-point nylon, acrylate resin, cross-linked acrylic, cross-linked styrene, cross-linked polyethylene, benzoguanamine, gold, aluminum, copper, and nickel. Additives may be used alone or in combination of two or more. Among these additives, silica, barium sulfate, and titanium oxide are preferred from the standpoints of dispersion stability and cost. The additives may also be subjected to various surface treatments, such as insulation treatments and high-dispersion treatments.

As described above, for example, when the exterior packaging material for an electricity storage device 10 is colored (specifically, when at least one layer (e.g., the substrate layer 1, adhesive layer 2, colored layer, or surface coating layer 6, as described below) of the exterior packaging material for an electricity storage device 10 located closer to the substrate layer 1 than the barrier layer 3 is colored, such that a color different from that of the barrier layer 3 is visible when the exterior packaging material for an electricity storage device 10 is observed from the substrate layer 1 side), whitening on the curved surface portion 11 or the like is likely to indicate a defective product. The quality control method of the present disclosure is particularly effective when the exterior packaging material for an electricity storage device 10 has a dark color, such as black. Furthermore, for example, when the exterior packaging material for an electricity storage device has a matte finish, whitening on the curved surface portion 11 or the like is likely to indicate a defective product, and the quality control method of the present disclosure is also effective. Therefore, in the exterior packaging material for an electricity storage device 10, the surface coating layer 6 may be colored, or it is preferable that the surface coating layer 6 contain a matting agent. Specifically, the quality control method of the present disclosure is effective when the surface coating layer 6 is made of a resin composition containing a resin (for example, polyurethane formed from a mixture of a polyol compound and an aromatic isocyanate compound), inorganic particles (for example, silica particles), and organic particles, and when the exterior packaging material 10 for an electricity storage device is observed from the surface coating layer 6 side, the appearance is a dark black color.

The method for forming the surface coating layer 6 is not particularly limited, and examples include a method of applying a resin to form the surface coating layer 6. If an additive is to be blended into the surface coating layer 6, a resin mixed with the additive may be applied.

The thickness of the surface coating layer 6 is not particularly limited as long as it exhibits the above-mentioned functions of the surface coating layer 6, but may be, for example, approximately 0.5 to 10 μm, and preferably approximately 1 to 5 μm.

Manufacturing Method of Sheathing Material for Electricity Storage Device The manufacturing method of the sheathing material for an electricity storage device is not particularly limited, as long as a laminate is obtained in which the layers of the sheathing material for an electricity storage device of the present invention are laminated, and examples include a method comprising a step of laminating at least the base material layer 1, the barrier layer 3, and the heat-sealable resin layer 4 in this order.

An example of a method for manufacturing an exterior material for an electricity storage device of the present invention is as follows. First, a laminate (hereinafter sometimes referred to as "laminate A") is formed in which a substrate layer 1, an adhesive layer 2, and a barrier layer 3 are laminated in this order. Specifically, laminate A can be formed by a dry lamination method in which the adhesive used to form adhesive layer 2 is applied to substrate layer 1 or, if necessary, to barrier layer 3 whose surface has been chemically treated, using a coating method such as gravure coating or roll coating, and then dried. Then, the barrier layer 3 or substrate layer 1 is laminated, and the adhesive layer 2 is cured.

Next, a heat-sealable resin layer 4 is laminated on the barrier layer 3 of the laminate A. When the heat-sealable resin layer 4 is laminated directly on the barrier layer 3, the heat-sealable resin layer 4 may be laminated on the barrier layer 3 of the laminate A by a method such as thermal lamination or extrusion lamination. Furthermore, when an adhesive layer 5 is provided between the barrier layer 3 and the heat-sealable resin layer 4, for example, (1) a method of laminating the adhesive layer 5 and the heat-sealable resin layer 4 by extruding them onto the barrier layer 3 of the laminate A (co-extrusion lamination, tandem lamination), (2) a method of separately forming a laminate in which the adhesive layer 5 and the heat-sealable resin layer 4 are laminated, and then laminating this on the barrier layer 3 of the laminate A by a thermal lamination, or a method of forming a laminate in which the adhesive layer 5 is laminated on the barrier layer 3 of the laminate A, and then laminating this with the heat-sealable resin layer 4 by a thermal lamination, (3) a method (sandwich lamination method) in which a molten adhesive layer 5 is poured between the barrier layer 3 of the laminate A and a heat-sealable resin layer 4 that has been pre-formed into a sheet, and the laminate A and the heat-sealable resin layer 4 are bonded together via the adhesive layer 5; (4) a method in which an adhesive for forming the adhesive layer 5 is solution-coated onto the barrier layer 3 of the laminate A, followed by drying or baking, and then the heat-sealable resin layer 4 that has been pre-formed into a sheet is laminated onto this adhesive layer 5.

When the surface coating layer 6 is provided, the surface coating layer 6 is laminated on the surface of the base layer 1 opposite the barrier layer 3. The surface coating layer 6 can be formed, for example, by applying the above-mentioned resin that forms the surface coating layer 6 to the surface of the base layer 1. The order of the step of laminating the barrier layer 3 on the surface of the base layer 1 and the step of laminating the surface coating layer 6 on the surface of the base layer 1 is not particularly limited. For example, after the surface coating layer 6 is formed on the surface of the base layer 1, the barrier layer 3 may be formed on the surface of the base layer 1 opposite the surface coating layer 6.

As described above, a laminate is formed comprising the optional surface coating layer 6, the substrate layer 1, the optional adhesive layer 2, the barrier layer 3, the optional adhesive layer 5, and the heat-sealable resin layer 4 in this order. To strengthen the adhesion of the optional adhesive layer 2 and adhesive layer 5, the laminate may be further subjected to a heat treatment.

In the packaging material for an electricity storage device, each layer constituting the laminate may be subjected to a surface activation treatment such as corona treatment, blast treatment, oxidation treatment, or ozone treatment, as necessary, to improve its processability. For example, corona treatment can be performed on the surface of the base layer 1 opposite the barrier layer 3, thereby improving the printability of ink on the surface of the base layer 1.

The exterior material for an electricity storage device according to the present disclosure is used in a package for hermetically housing an electricity storage device element such as a positive electrode, a negative electrode, an electrolyte, etc. That is, an electricity storage device can be formed by housing an electricity storage device element including at least a positive electrode, a negative electrode, and an electrolyte in a package formed from the exterior material for an electricity storage device according to the present disclosure.

Specifically, an electricity storage device using the electricity storage device packaging material of the present disclosure is provided by covering an electricity storage device element including at least a positive electrode, a negative electrode, and an electrolyte with the electricity storage device packaging material of the present disclosure, with metal terminals connected to the positive electrode and negative electrode protruding outward, so that a flange portion (a region where the heat-sealable resin layers contact each other) is formed around the periphery of the electricity storage device element, and the heat-sealable resin layers of the flange portion are heat-sealed to form a hermetic seal. When an electricity storage device element is housed in a package formed from the electricity storage device packaging material of the present disclosure, the package is formed so that the heat-sealable resin portion of the electricity storage device packaging material of the present disclosure faces inward (the surface that contacts the electricity storage device element). A package may be formed by overlapping two electrical storage device exterior packaging materials with the heat-sealable resin layers facing each other and heat-sealing the peripheral edges of the overlapped electrical storage device exterior packaging materials. Alternatively, as shown in the example of FIG. 11, one electrical storage device exterior packaging material may be folded over and overlapped, and the peripheral edges may be heat-sealed to form a package. When folding and overlapping, as shown in the example of FIG. 11, the edges other than the folded edge may be heat-sealed to form a package with a three-sided seal, or the material may be folded over to form a flange and sealed on all four sides. Furthermore, a recess for accommodating an electrical storage device element may be formed in the electrical storage device exterior packaging material by deep drawing or bulging molding. As shown in the example of FIG. 11, one electrical storage device exterior packaging material may have a recess and the other electrical storage device exterior material may not have a recess, or the other electrical storage device exterior material may also have a recess.

The exterior packaging material for an electricity storage device of the present disclosure can be suitably used in electricity storage devices such as batteries (including condensers, capacitors, etc.). The exterior packaging material for an electricity storage device of the present disclosure may be used in either primary or secondary batteries, but is preferably used in secondary batteries. The type of secondary battery to which the exterior packaging material for an electricity storage device of the present disclosure can be applied is not particularly limited, and examples include lithium-ion batteries, lithium-ion polymer batteries, all-solid-state batteries, lead-acid batteries, nickel-metal hydride batteries, nickel-cadmium batteries, nickel-iron batteries, nickel-zinc batteries, silver oxide-zinc batteries, metal-air batteries, polyvalent cation batteries, condensers, and capacitors. Among these secondary batteries, lithium-ion batteries and lithium-ion polymer batteries are suitable applications for the exterior packaging material for an electricity storage device of the present disclosure.

The present disclosure will be explained in detail below using examples. However, the present disclosure is not limited to these examples.

<Manufacturing of exterior materials for electricity storage devices>
Examples 1-6
An oriented nylon (ONy) film (thickness: 15 μm) was prepared as the substrate layer. Furthermore, aluminum foil (JIS H4160:1994 A8021H-O (thickness: 35 μm)) was prepared as the barrier layer. Next, the barrier layer and the substrate layer were laminated by dry lamination using an adhesive (a two-component urethane adhesive containing carbon black as a colorant), followed by aging treatment to produce a substrate layer/adhesive layer (black)/barrier layer laminate. Both sides of the aluminum foil were subjected to a chemical conversion treatment. The chemical conversion treatment of the aluminum foil was performed by roll coating a treatment solution consisting of a phenolic resin, a chromium fluoride compound, and phosphoric acid onto both sides of the aluminum foil so that the coating amount of chromium was 10 mg/m ² (dry mass), followed by baking.

Next, maleic anhydride-modified polypropylene as an adhesive layer (20 μm thick) and random polypropylene as a heat-sealable resin layer (15 μm thick) were co-extruded onto the barrier layer of each of the laminates obtained above, thereby laminating the adhesive layer and heat-sealable resin layer on top of the barrier layer. Furthermore, a resin composition having the composition described below (the resin is a polyurethane resin formed from a mixture of a polyol compound and an isocyanate compound) was applied to the surface of the substrate layer of each of the obtained laminates to a thickness of 3 μm to form a matte surface coating layer, resulting in a laminate (total thickness 91 μm) consisting of, from outside in, the surface coating layer (3 μm), substrate layer (15 μm thick), adhesive layer (3 μm), barrier layer (35 μm), adhesive layer (20 μm), and heat-sealable resin layer (15 μm).

Next, each of the resulting laminates was cut into strips measuring 150 mm (TD; Transverse Direction) x 90 mm (MD; Machine Direction). The MD of the laminate corresponds to the rolling direction (RD) of the aluminum alloy foil, and the TD of the laminate corresponds to the TD of the aluminum alloy foil. The strips were then placed between a 54.5 mm (TD) x 31.6 mm (MD) female mold and a corresponding male mold (female mold) (with the female mold side facing the substrate layer). Cold forming was performed using four cylinders (cylinder diameter φ80 mm) with a cylinder pressure of 0.25 MPa to a forming depth D = 3.0 mm, resulting in a black exterior packaging material for an electricity storage device with rectangular recesses 100 in plan view, as shown in the schematic diagrams of Figures 5 and 6.

The clearance between the female and male molds was 0.5 mm. The surface of the female mold had a maximum height roughness (nominal Rz value) of 0.8 μm as specified in Table 2 of the comparative surface roughness standard specimen in JIS B 0659-1:2002, Appendix 1 (Reference). The corner R of the female mold was 2.0 mm and the ridge R was 2.5 mm. The surface of the male mold had a maximum height roughness (nominal Rz value) of 3.2 μm as specified in Table 2 of the comparative surface roughness standard specimen in JIS B 0659-1:2002, Appendix 1 (Reference). The corner R of the male mold was 2.0 mm and the ridge R was 2.0 mm. The corner R and ridge R of the male mold have a maximum height roughness (nominal Rz value) of 1.6 μm, as specified in Table 2 of the comparative surface roughness standard specimen in JIS B 0659-1:2002, Appendix 1 (Reference).

Example 7
An oriented nylon (ONy) film (thickness: 12 μm) was prepared as the substrate layer. A stainless steel foil (SUS304 (thickness: 20 μm)) was prepared as the barrier layer. The barrier layer and substrate layer were then laminated by dry lamination using an adhesive (a two-component urethane adhesive containing carbon black as a colorant), followed by aging treatment to produce a substrate layer/adhesive layer (black)/barrier layer laminate. Both sides of the stainless steel foil were subjected to a chemical conversion treatment. The chemical conversion treatment of the stainless steel foil was performed by roll coating a treatment solution consisting of a phenolic resin, a chromium fluoride compound, and phosphoric acid onto both sides of the stainless steel foil so that the chromium coating amount was 10 mg/ ^m2 (dry mass), followed by baking.

Next, the barrier layer and heat-sealable resin layer of the resulting laminate were dry-laminated using a modified olefin-based adhesive (adhesive layer thickness after curing: 3 μm), and the adhesive layer and heat-sealable resin layer were laminated on top of the barrier layer. An unstretched polypropylene film (thickness: 23 μm) was used as the heat-sealable resin layer. Furthermore, a matte surface coating layer was formed by coating the surface of the substrate layer of the resulting laminate with Resin Composition 2 (described below) (a polyurethane resin formed from a mixture of a polyol compound and an isocyanate compound) to a thickness of 3 μm. This resulted in a laminate (total thickness: 64 μm) consisting of, from outside, the surface coating layer (3 μm), substrate layer (thickness: 12 μm), adhesive layer (3 μm), barrier layer (20 μm), adhesive layer (3 μm), and heat-sealable resin layer (23 μm). The obtained laminate was molded in the same manner as in Examples 1 to 6 to obtain an exterior material for an electricity storage device with a black appearance and rectangular recesses 100 in plan view, as shown in the schematic diagrams of Figures 5 and 6.

Example 8
An exterior material for a storage battery device having a black appearance and rectangular recesses 100 in plan view as shown in the schematic diagrams of Figures 5 and 6 was obtained in the same manner as in Example 7, except that in forming the surface coating layer, resin composition 3 below was used instead of resin composition 2.

[Resin composition for surface coating layer]
In the examples, the surface coating layers were formed using resin compositions having the following formulations.

(Resin Composition 1 (Used in Example 1))
A resin composition containing a resin (polyurethane formed from a mixture of one type of polyol compound and an aliphatic isocyanate compound), inorganic particles (barium sulfate particles, average particle size 1 μm), organic particles (average particle size 2 μm), and an olefin wax.

(Resin Composition 2 (used in Examples 2 and 7))
A resin composition comprising a resin (polyurethane formed from a mixture of two types of polyol compounds and an aliphatic isocyanate compound), inorganic particles (silica particles, average particle size 1 μm), organic particles (average particle size 2 μm), and an olefin wax.

(Resin Composition 3 (used in Examples 3 and 8))
A resin composition comprising a resin (polyurethane formed from a mixture of two types of polyol compounds and an aromatic isocyanate compound (the blending ratio of the two types of polyol compounds was changed from that of Resin Composition 2)), inorganic particles (silica particles, average particle size: 1 μm), and organic particles (average particle size: 2 μm).

(Resin Composition 4 (Used in Example 4))
The resin composition of Example 2 with a reduced content of inorganic particles.

(Resin Composition 5 (Used in Example 5))
The resin composition of Example 3 with a reduced content of inorganic particles.

(Resin Composition 6 (Used in Example 6))
A resin composition comprising a resin (polyurethane formed from a mixture of two types of polyol compounds and an aromatic isocyanate compound (the blending ratio of the two types of polyol compounds was changed from that of the resin composition of Example 3)), inorganic particles (silica particles, average particle size 1 μm), organic particles (average particle size 2 μm), and an olefin wax.

<Judgment process>
The L* value, a* value, and b* value in the L*a*b* color space were measured under the following conditions for each of the curved portions on the outer surface of the base layer side that form the recesses of each of the electrical storage device packaging materials obtained in the examples, which are curved portions that protrude toward the base layer side of the electrical storage device packaging material (curved portion 11 shown in the schematic diagrams of FIGS. 5 ^and 6), and the ^uncurved portions on the outer surface of the base layer side that form the recesses (uncurved portion 12 ⁽ center portion of recess ¹⁰⁰ ) shown in the schematic diagrams of FIGS. ⁵ and ⁶ ). The observation conditions of a Konica Minolta spectrophotometer (CM-700d) calibrated with a white calibration cap (CM-A177: manufactured by Konica Minolta) were set to 10°, the observation illuminant was F2, and SCI mode (JIS Z8722-2009). Next, the L ^* , a ^* , and b ^* values of the outer (substrate layer side) surfaces of the curved and non-curved portions were measured at room temperature and humidity. The measurement diameter was set to 8 mm for the curved portion, and 3 mm for the non-curved portion. The ΔE ^* ab value was calculated based on the formula: ΔE ^* ab = [(ΔL) ² + (Δa) ² + (Δb) ² ] ^1/2 . The results are shown in Table 1. In Table 1, the L ^* value is rounded to one decimal place, and the a ^* and b ^* values are rounded to two decimal places. The evaluation process confirmed that the absolute value of the difference in the L ^* values between the curved and non-curved portions was 1.5 or less in Examples 1 to 5, 7, and 8, and that the absolute value of the difference exceeded 1.5 in Example 6.

<Observation by scanning electron microscope>
Next, the curved surface portions for which the L ^* value, a ^* value, and b ^* value were measured in the above-mentioned <judgment step> were observed with a scanning electron microscope (magnification 1,000x). The obtained images are shown in Figure 7 (Example 1), Figure 8 (Example 2), Figure 9 (Example 3), and Figure 10 (Example 6), respectively. As a result, in the electrical storage device packaging materials of Examples 1 to 5, in which the absolute value of the difference in L ^* value was 1.5 or less, no cracks occurred in the curved surface portions, and they could be judged as good products. In the electrical storage device packaging materials of Examples 7 and 8, no cracks occurred in the curved surface portions, and they could be judged as good products. On the other hand, in the electrical storage device packaging material of Example 6, in which the absolute value of the difference in L ^* value was greater than 1.5, very fine cracks occurred in the curved surface portions, and they could be judged as defective products in the above-mentioned judgment step. As mentioned above, the absolute value of the difference in L ^* value being 1.5 or less is one example of a judgment criterion, and this judgment criterion does not have to be adopted in the quality control method and manufacturing method of an electrical storage device of the present disclosure. The cracks observed with a scanning electron microscope were evaluated according to the following criteria. The results are shown in Table 1.
A: No cracks were observed.
B: Cracks are present, but each crack is small and there are only a few cracks.
C: Cracks are present, each large, and there are a great number of cracks.

<Appearance evaluation>
In the evaluation step, the curved surface portion and the non-curved surface portion for which the L ^* value, a ^* value, and b ^* value had been measured were visually inspected for appearance by an expert in evaluating whitening due to molding of exterior materials for electricity storage devices, and evaluated according to the following criteria. The results are shown in Table 1.
A: The appearance of the curved surface portion and the non-curved surface portion are similar.
B: Compared with the non-curved surface portion, the curved surface portion is judged to be slightly whitened, but the whitening is so slight that even an experienced person would find it difficult to judge.
C: Compared with the non-curved surface portion, the curved surface portion is judged to be slightly whitened, but the whitening is so slight that it is somewhat difficult for an unskilled person to judge.

<Measurement of specular gloss>
The specular gloss of the outer surface of the surface coating layer of each electrical storage device exterior material before molding was measured by the following measurement method. In accordance with the method specified in JIS Z 8741 (1997), the specular gloss of the surface coating layer was measured at an incident angle of 60 degrees using a gloss measuring instrument, Micro-Tri-Gloss (measurement area: 9 mm x 15 mm), manufactured by Toyo Seiki Seisakusho, Ltd. The results are shown in Table 1. The specular gloss values listed in Table 1 are values obtained by rounding off the measured values to one decimal place.

The results of Examples 1 to 8 show that by applying the quality control method of the present disclosure to the molding process of an electrical storage device exterior material, it is possible to determine whether an electrical storage device exterior material having a recess formed therein is a good product based on the magnitude of the L ^* value of the curved and uncurved portions forming the recess. This quality control method is a novel quality control method and can provide more accurate quality control than conventional quality control using visual inspection or a camera. Therefore, by utilizing the quality control method of the present disclosure in the manufacture of electrical storage devices, it is possible to more efficiently manufacture good electrical storage devices. Note that, in observation with a scanning electron microscope, specimens with a crack rating of B had small and few cracks in the curved portion, which meant the cracks were not continuous, and the surface coating layer existed as a film. On the other hand, specimens with a crack rating of C had large and numerous cracks, which meant the cracks in the curved portion were continuous, and the surface coating layer existed in island-like patterns, making them prone to peeling.

<Evaluation of electrolyte resistance>
In a room temperature (23 ° C) environment, the L ^* value, a ^* value, and b ^* value were measured for the outer surface (outer surface of the surface coating layer) of each of the molded electrical storage device exterior materials obtained in Examples 3, 5, 6, 7, and 8. Three drops of electrolyte (1 mol / liter lithium hexafluorophosphate solution, solvent: ethylene carbonate: diethyl carbonate: dimethyl carbonate = 1:1:1 (volume ratio)) were dripped onto the non-bent and curved portions, respectively, and after 20 minutes, the dripped electrolyte was wiped off with a wipe soaked in isopropyl alcohol (IPA). Next, the curved portions were visually observed, and the electrolyte resistance was evaluated according to the following criteria. The results are shown in Table 2.
A: No peeling of the surface coating layer is observed.
C: Peeling of the surface coating layer is observed.

The electrical storage device packaging materials produced in Examples 1 to 8 have a matte finish containing inorganic particles in the surface coating layer, and therefore can be said to be electrical storage device packaging materials that are prone to the occurrence of fine cracks due to molding. Despite being such electrical storage device packaging materials, a comparison of the evaluation of electrolyte resistance between Examples 3, 5, 7, and 8 and Example 6 shows that Examples 3, 5, 7, and 8, in which the absolute value of the difference between the L ^* value of the curved portion and the L ^* value of the uncurved portion 12 is controlled to 1.5 or less, have particularly excellent electrolyte resistance.

As described above, the present disclosure provides the following aspects of the invention.
Item 1. A quality control method in a molding process of an exterior material for an electricity storage device, comprising:
The quality control method targets quality control of an electrical storage device packaging material that is made of a laminate including at least a base material layer, a barrier layer, and a heat-sealable resin layer in this order from the outside, and that is molded so as to protrude from the heat-sealable resin layer side toward the base material layer side, and that has a recess formed on the heat-sealable resin layer side in which an electrical storage device element is housed,
a determining step of extracting a test-target electrical storage device exterior material from among the electrical storage device exterior materials in which the recesses are formed, measuring the L* value in the L ^* a*b ^* color space of reflected light for each of the curved and ^uncurved portions of the outer surface that form the recesses of the test-target electrical storage device exterior material under measurement conditions of an SCI method, a field of view of ¹⁰ °, and a light source F2, and determining whether the electrical storage device exterior material in which the recesses are formed is a non-defective product based on the magnitude of the difference in ^the L* value;
A quality control method for the molding process of exterior materials for electricity storage devices.
Item 2. The quality control method according to Item 1, wherein in the judging step, a product is judged to be non-defective when the absolute value of the difference between the L ^* value of the curved surface portion and the L ^* value of the non-curved surface portion is 1.5 or less.
Item 3. The quality control method according to Item 1 or 2, wherein the packaging material for an electricity storage device includes a surface coating layer on the outside of the base material layer.
Item 4. The packaging material for an electricity storage device includes an adhesive layer between the base material layer and the barrier layer,
Item 4. The quality control method according to any one of Items 1 to 3, wherein the adhesive layer is colored.
Item 5. A method for manufacturing an electricity storage device, in which an electricity storage device element is sealed with a packaging body formed by heat-sealing the heat-sealable resin layer around the periphery of an exterior packaging material for an electricity storage device, the packaging material being composed of a laminate including, in this order from the outside, at least a base material layer, a barrier layer, and a heat-sealable resin layer,
The method for manufacturing the electricity storage device includes the steps of: preparing an exterior material for an electricity storage device, the exterior material having a recess formed therein, the recess protruding from the heat-sealable resin layer side of the exterior material for an electricity storage device toward the base layer side, and accommodating an electricity storage device element;
a determining step of extracting a test-target electrical storage device exterior material from among the electrical storage device exterior materials in which the recesses are formed, measuring the L* value in the L ^* a*b ^* color space of reflected light for each of the curved and ^uncurved portions of the outer surface that form the recesses of the test-target electrical storage device exterior material under measurement conditions of an SCI method, a field of view of ¹⁰ °, and a light source F2, and determining whether the electrical storage device exterior material in which the recesses are formed is a non-defective product based on the magnitude of the difference in ^the L* value;
a step of manufacturing an electricity storage device by accommodating an electricity storage device element in the recess of the exterior material for the electricity storage device;
It is equipped with
If the result of the determination step is that the molded exterior material for an electricity storage device is determined to be a good product, the method for manufacturing an electricity storage device determines that the formation of the recess is appropriate, and houses an electricity storage device element in the recess to manufacture the electricity storage device.
Item 6. The method for manufacturing an electricity storage device according to Item 5, wherein in the determining step, a product is determined to be non-defective when the absolute value of the difference between the L ^* value of the curved surface portion and the L ^* value of the non-curved surface portion is 1.5 or less.
Item 7. The method for producing an electricity storage device according to Item 5 or 6, wherein the exterior packaging material for an electricity storage device includes a surface coating layer on the outside of the base material layer.
Item 8. The packaging material for an electricity storage device includes an adhesive layer between the base layer and the barrier layer,
Item 8. The method for producing an electricity storage device according to any one of Items 5 to 7, wherein the adhesive layer is colored.
Item 9. A method for inspecting an exterior material for an electricity storage device having a recess formed therein, comprising:
The inspection method inspects an electrical storage device packaging material that is made of a laminate including at least a base material layer, a barrier layer, and a heat-sealable resin layer in this order from the outside, and that is molded so as to protrude from the heat-sealable resin layer side toward the base material layer side, and that has a recess formed on the heat-sealable resin layer side in which an electrical storage device element is housed,
a determining step of measuring the L* value in the L ^* a*b* color space of reflected light for each of the curved surface portion and the non- ^curved surface portion of the outer surface forming the recess of the electrical storage device packaging material in which the recess is formed, using the ^SCI method, a field of view of 10 ^° , and a light source ^F2 , and determining whether the electrical storage device packaging material in which the recess is formed is a non-defective product based on the magnitude of the difference in the L* value;
A method for inspecting an exterior material for an electricity storage device having a recess formed therein.
Item 10. The inspection method according to Item 9, wherein in the determining step, a product is determined to be non-defective when the absolute value of the difference between the L ^* value of the curved surface portion and the L ^* value of the non-curved surface portion is 1.5 or less.
Item 11. The inspection method according to Item 9 or 10, wherein the electrical storage device packaging material includes a surface coating layer on the outside of the base material layer.
Item 12. An exterior packaging material for an electricity storage device composed of a laminate including, in order from the outside, at least a base material layer, a barrier layer, and a heat-sealable resin layer,
the electrical storage device packaging material is molded so as to protrude from the thermally adhesive resin layer side to the base material layer side, and includes a recess on the thermally adhesive resin layer side in which an electrical storage device element is housed,
The exterior material for an electrical storage device, wherein when the L* value in the L ^* a ^* b ^* color space of reflected light is measured for each of the curved and non ^{-curved portions of the outer surface forming the recess of the exterior material for an electrical storage device using the SCI method, a field of view of 10°, and measurement conditions of light source F2, the absolute value of the difference between the L* value} of the curved portion and the L ^* value of the non-curved portion is 1.5 or less.
Item 13. The packaging material for an electricity storage device according to Item 12, wherein the packaging material for an electricity storage device includes a surface coating layer on the outside of the base material layer.
Item 14. The packaging material for an electricity storage device includes an adhesive layer between the base layer and the barrier layer,
Item 14. The packaging material for an electricity storage device according to Item 12 or 13, wherein the adhesive layer is colored.
Item 15. An exterior packaging material for an electricity storage device composed of a laminate including, in order from the outside, at least a base material layer, a barrier layer, and a heat-sealable resin layer,
The electrical storage device exterior material is molded under the following molding conditions so as to protrude from the heat-sealable resin layer side to the base layer side, forming a recess on the heat-sealable resin layer side in which an electrical storage device element is housed, and when the L ^* value in the L*a*b* color space of reflected light is measured for each of the curved and ^uncurved portions of the outer surface that form the recess of the electrical storage device exterior material using the SCI method, a field of view of 10°, and light source F2, the ^absolute value of the difference between the L ^* value of the curved portion and ^the L ^* value of the uncurved portion is 1.5 or less.
(Molding conditions)
The electrical storage device exterior material is placed between a molding die (female die) with a diameter of 54.5 mm (TD) x 31.6 mm (MD) and a corresponding molding die (male die) with the female die facing the substrate layer, and cold-formed at a pressing pressure (surface pressure) of 0.25 MPa and a molding depth of 3.0 mm to form a rectangular recess in plan view. The clearance between the female die and the male die is 0.5 mm. The surface of the female die has a maximum height roughness (nominal Rz value) of 0.8 μm, as specified in Table 2 of the comparative surface roughness standard specimen in JIS B 0659-1:2002, Appendix 1 (Reference). The corner R of the female die is 2.0 mm, and the ridge R is 2.5 mm. The surface of the male mold has a maximum height roughness (nominal Rz value) of 3.2 μm as specified in Table 2 of the comparative surface roughness standard specimen in Appendix 1 of JIS B 0659-1:2002 (reference). The corner R of the male mold is 2.0 mm, and the ridge R is 2.0 mm. The corner R and ridge R of the male mold have a maximum height roughness (nominal Rz value) of 1.6 μm as specified in Table 2 of the comparative surface roughness standard specimen in Appendix 1 of JIS B 0659-1:2002 (reference).
Item 16. The packaging material for an electricity storage device according to Item 15, wherein the packaging material for an electricity storage device includes a surface coating layer on the outside of the base material layer.
Item 17. The packaging material for an electricity storage device includes an adhesive layer between the base material layer and the barrier layer,
Item 17. The packaging material for an electricity storage device according to Item 15 or 16, wherein the adhesive layer is colored.
Item 18. An electricity storage device, in which an electricity storage device element including at least a positive electrode, a negative electrode, and an electrolyte is housed in a package formed from the exterior material for an electricity storage device according to any one of Items 12 to 14.

REFERENCE SIGNS LIST 1 Base material layer 2 Adhesive layer 3 Barrier layer 4 Thermally adhesive resin layer 5 Adhesive layer 6 Surface coating layer 10 Electricity storage device packaging material 11 Curved surface portion 11a Corner portion 11b Ridge line portion 12 Non-curved surface portion 13 Curved surface portion 14 Peripheral edge portion 100 Recessed portion

Claims (21)

An exterior material for an electricity storage device, which is composed of a laminate including, in order from the outside, at least a surface coating layer, a base material layer, a barrier layer, and a heat-sealable resin layer,
the surface coating layer is formed from a resin composition containing polyurethane,
the surface coating layer contains an additive,
the additive is at least one of an organic substance and an inorganic substance,
the electrical storage device packaging material is molded so as to protrude from the thermally adhesive resin layer side to the base material layer side, and includes a recess on the thermally adhesive resin layer side in which an electrical storage device element is housed,
The exterior material for an electrical storage device, wherein when the L* value in the L ^* a ^* b ^* color space of reflected light is measured for each of the curved and non ^{-curved portions of the outer surface forming the recess of the exterior material for an electrical storage device using the SCI method, a field of view of 10°, and measurement conditions of light source F2, the absolute value of the difference between the L* value} of the curved portion and the L ^* value of the non-curved portion is 1.5 or less. An exterior material for an electricity storage device, which is composed of a laminate including, in order from the outside, at least a surface coating layer, a base material layer, a barrier layer, and a heat-sealable resin layer,
the surface coating layer is formed from a resin composition containing polyurethane,
The polyurethane is a polyurethane containing a base agent containing a polyol compound and a curing agent containing an aromatic isocyanate compound,
the electrical storage device packaging material is molded so as to protrude from the thermally adhesive resin layer side to the base material layer side, and includes a recess on the thermally adhesive resin layer side in which an electrical storage device element is housed,
The exterior material for an electrical storage device, wherein when the L* value in the L ^* a ^* b ^* color space of reflected light is measured for each of the curved and non ^{-curved portions of the outer surface forming the recess of the exterior material for an electrical storage device using the SCI method, a field of view of 10°, and measurement conditions of light source F2, the absolute value of the difference between the L* value} of the curved portion and the L ^* value of the non-curved portion is 1.5 or less. An exterior material for an electricity storage device, which is composed of a laminate including, in order from the outside, at least a surface coating layer, a base material layer, a barrier layer, and a heat-sealable resin layer,
the surface coating layer is formed from a resin composition containing polyurethane,
the surface coating layer contains an additive,
the additive is at least one of an organic substance and an inorganic substance,
The electrical storage device exterior material is molded under the following molding conditions so as to protrude from the heat-sealable resin layer side to the base layer side, forming a recess on the heat-sealable resin layer side in which an electrical storage device element is housed, and when the L ^* value in the L*a*b* color space of reflected light is measured for each of the curved and ^uncurved portions of the outer surface that form the recess of the electrical storage device exterior material using the SCI method, a field of view of 10°, and light source F2, the ^absolute value of the difference between the L ^* value of the curved portion and ^the L ^* value of the uncurved portion is 1.5 or less.
(Molding conditions)
The electrical storage device exterior material is placed between a molding die (female die) with a diameter of 54.5 mm (TD) x 31.6 mm (MD) and a corresponding molding die (male die) with the female die facing the substrate layer, and cold-formed at a pressing pressure (surface pressure) of 0.25 MPa and a molding depth of 3.0 mm to form a rectangular recess in plan view. The clearance between the female die and the male die is 0.5 mm. The surface of the female die has a maximum height roughness (nominal Rz value) of 0.8 μm, as specified in Table 2 of the comparative surface roughness standard specimen in JIS B 0659-1:2002, Appendix 1 (Reference). The corner R of the female die is 2.0 mm, and the ridge R is 2.5 mm. The surface of the male mold has a maximum height roughness (nominal Rz value) of 3.2 μm as specified in Table 2 of the comparative surface roughness standard specimen in Appendix 1 of JIS B 0659-1:2002 (reference). The corner R of the male mold is 2.0 mm, and the ridge R is 2.0 mm. The corner R and ridge R of the male mold have a maximum height roughness (nominal Rz value) of 1.6 μm as specified in Table 2 of the comparative surface roughness standard specimen in Appendix 1 of JIS B 0659-1:2002 (reference). An exterior material for an electricity storage device, which is composed of a laminate including, in order from the outside, at least a surface coating layer, a base material layer, a barrier layer, and a heat-sealable resin layer,
the surface coating layer is formed from a resin composition containing polyurethane,
The polyurethane is a polyurethane containing a base agent containing a polyol compound and a curing agent containing an aromatic isocyanate compound,
The electrical storage device exterior material is molded under the following molding conditions so as to protrude from the heat-sealable resin layer side to the base layer side, forming a recess on the heat-sealable resin layer side in which an electrical storage device element is housed, and when the L ^* value in the L*a*b* color space of reflected light is measured for each of the curved and ^uncurved portions of the outer surface that form the recess of the electrical storage device exterior material using the SCI method, a field of view of 10°, and light source F2, the ^absolute value of the difference between the L ^* value of the curved portion and ^the L ^* value of the uncurved portion is 1.5 or less.
(Molding conditions)
The electrical storage device exterior material is placed between a molding die (female die) with a diameter of 54.5 mm (TD) x 31.6 mm (MD) and a corresponding molding die (male die) with the female die facing the substrate layer, and cold-formed at a pressing pressure (surface pressure) of 0.25 MPa and a molding depth of 3.0 mm to form a rectangular recess in plan view. The clearance between the female die and the male die is 0.5 mm. The surface of the female die has a maximum height roughness (nominal Rz value) of 0.8 μm, as specified in Table 2 of the comparative surface roughness standard specimen in JIS B 0659-1:2002, Appendix 1 (Reference). The corner R of the female die is 2.0 mm, and the ridge R is 2.5 mm. The surface of the male mold has a maximum height roughness (nominal Rz value) of 3.2 μm as specified in Table 2 of the comparative surface roughness standard specimen in Appendix 1 of JIS B 0659-1:2002 (reference). The corner R of the male mold is 2.0 mm, and the ridge R is 2.0 mm. The corner R and ridge R of the male mold have a maximum height roughness (nominal Rz value) of 1.6 μm as specified in Table 2 of the comparative surface roughness standard specimen in Appendix 1 of JIS B 0659-1:2002 (reference). The exterior material for an electricity storage device according to claim 1 or 3, wherein the additive comprises titanium oxide. The exterior packaging material for an electricity storage device according to claim 2 or 4, wherein the aromatic isocyanate compound includes xylylene diisocyanate (XDI). The exterior material for an electricity storage device according to any one of claims 1 to 6, wherein the surface coating layer is colored. the packaging material for an electricity storage device includes an adhesive layer between the base layer and the barrier layer,
The packaging material for an electricity storage device according to any one of claims 1 to 7, wherein the adhesive layer is colored. The exterior material for an electricity storage device according to any one of claims 1 to 8, wherein two or more types of lubricants are present on at least one of the surface and interior of the base material layer. The exterior material for an electricity storage device according to any one of claims 1 to 9, wherein at least two selected from the group consisting of saturated fatty acid amides, unsaturated fatty acid amides, substituted amides, methylol amides, saturated fatty acid bisamides, unsaturated fatty acid bisamides, fatty acid ester amides, and aromatic bisamides are present on at least one of the surface and interior of the base layer. The electrical storage device packaging material according to any one of claims 1 to 10, wherein the barrier layer includes at least one of aluminum alloy foil and stainless steel foil. The packaging material for an electricity storage device according to any one of claims 1 to 11, wherein two or more types of lubricants are present on at least one of the surface and interior of the heat-sealable resin layer. The exterior packaging material for an electricity storage device according to any one of claims 1 to 12, wherein at least two selected from the group consisting of saturated fatty acid amides, unsaturated fatty acid amides, substituted amides, methylol amides, saturated fatty acid bisamides, unsaturated fatty acid bisamides, fatty acid ester amides, and aromatic bisamides are present on at least one of the surface and interior of the heat-sealable resin layer. The electrical storage device packaging material according to any one of claims 1 to 13, wherein the electrical storage device packaging material includes a colored layer between the base layer and the barrier layer. The exterior material for an electricity storage device according to any one of claims 1 to 14, wherein two or more types of lubricants are present on at least one of the surface and interior of the surface coating layer. The exterior material for an electricity storage device according to any one of claims 1 to 15, wherein at least one selected from the group consisting of saturated fatty acid amides, unsaturated fatty acid amides, substituted amides, methylol amides, saturated fatty acid bisamides, unsaturated fatty acid bisamides, fatty acid ester amides, and aromatic bisamides is present on at least one of the surface and interior of the surface coating layer. An electricity storage device in which an electricity storage device element having at least a positive electrode, a negative electrode, and an electrolyte is housed in a package formed from the exterior packaging material for an electricity storage device according to any one of claims 1 to 16. The method includes a step of obtaining an exterior material for an electricity storage device, which is composed of a laminate in which at least a surface coating layer, a base material layer, a barrier layer, and a heat-sealable resin layer are laminated in this order,
the surface coating layer is formed from a resin composition containing polyurethane,
the electrical storage device packaging material is molded so as to protrude from the thermally adhesive resin layer side to the base material layer side, and includes a recess on the thermally adhesive resin layer side in which an electrical storage device element is housed,
When the L* value in the L ^* a ^* b ^* color space of reflected light is measured for each of the curved surface portion and the non ^{-curved surface portion on the outer surface forming the recess of the exterior material for an electricity storage device under measurement conditions of an SCI method, a field of view of 10°, and a light source F2, the absolute value of the difference between the L* value} of the curved surface portion and the L ^* value of the non-curved surface portion is 1.5 or less,
the surface coating layer contains an additive,
The method for producing an exterior material for an electricity storage device, wherein the additive is at least one of an organic substance and an inorganic substance. The method includes a step of obtaining an exterior material for an electricity storage device, which is composed of a laminate in which at least a surface coating layer, a base material layer, a barrier layer, and a heat-sealable resin layer are laminated in this order,
the surface coating layer is formed from a resin composition containing polyurethane,
the electrical storage device packaging material is molded so as to protrude from the thermally adhesive resin layer side to the base material layer side, and includes a recess on the thermally adhesive resin layer side in which an electrical storage device element is housed,
When the L* value in the L ^* a ^* b ^* color space of reflected light is measured for each of the curved surface portion and the non ^{-curved surface portion on the outer surface forming the recess of the exterior material for an electricity storage device under measurement conditions of an SCI method, a field of view of 10°, and a light source F2, the absolute value of the difference between the L* value} of the curved surface portion and the L ^* value of the non-curved surface portion is 1.5 or less,
A method for producing an exterior material for an electrical storage device, wherein the polyurethane is a polyurethane containing a base agent containing a polyol compound and a curing agent containing an aromatic isocyanate compound. an adhesive layer is provided between the barrier layer and the heat-sealable resin layer,
20. The method for producing an exterior material for an electricity storage device according to claim 18 or 19, wherein the adhesive layer and the heat-sealable resin layer are formed by a co-extrusion lamination method, a tandem lamination method, a thermal lamination method, a sandwich lamination method, or a method of laminating an adhesive for forming the adhesive layer on the barrier layer, and laminating the heat-sealable resin layer, which has been formed in advance into a sheet shape, on the adhesive layer. The method for manufacturing an exterior material for an electricity storage device according to any one of claims 18 to 20, wherein the heat-sealable resin layer is formed of two or more layers of the same or different resins.