Exterior material for power storage device, manufacturing method thereof, and power storage device

Abstract

Provided is a cold-formable exterior material for an electricity storage device that is composed of a laminate having at least a base layer, an adhesive layer, a barrier layer, and a heat-sealable resin layer in this order, and that has excellent resistance to moist heat. [Solution] An exterior packaging material 10 for an electricity storage device is composed of a laminate having at least a base material layer 1, an adhesive layer 2, a barrier layer 3, and a heat-sealable resin layer 4 in this order, the adhesive layer having moisture and heat resistance, and the laminate being cold-formable.

Description

[Technical Field]

[0001] The present disclosure relates to an exterior material for an electricity storage device, a method for producing the same, and an electricity storage device. [Background technology]

[0002] Various types of electricity storage devices have been developed, but in all of them, packaging materials (exterior materials) are essential components for sealing the electricity storage device elements such as electrodes and electrolytes. Conventionally, metal exterior materials have been widely used as exterior materials for electricity storage devices.

[0003] Meanwhile, in recent years, with the increasing performance of electric vehicles, hybrid electric vehicles, personal computers, cameras, mobile phones, etc., electricity storage devices are being required to have a variety of shapes as well as to be thinner and lighter in weight. However, the metallic exterior materials for electricity storage devices that have been widely used in the past have the drawbacks of being difficult to keep up with the diversification of shapes and also having limitations on how much they can be made lighter.

[0004] Therefore, in recent years, a film-like packaging material in which a substrate / aluminum alloy foil layer / thermally adhesive resin layer are sequentially laminated has been proposed as a packaging material for an electricity storage device that can be easily processed into various shapes and can be made thinner and lighter (see, for example, Patent Document 1).

[0005] In such film-like packaging materials, recesses are generally formed by cold forming, and energy storage device elements such as electrodes and electrolyte are placed in the spaces formed by the recesses. The heat-sealable resin layers are then heat-sealed together to obtain an energy storage device in which the energy storage device elements are housed inside the packaging material. [Prior art documents] [Patent documents]

[0006] [Patent Document 1] Japanese Patent Application Laid-Open No. 2008-287971 Summary of the Invention [Problem to be solved by the invention]

[0007] As described above, film-like packaging materials for electricity storage devices, in which a substrate, an aluminum alloy foil layer, and a heat-sealable resin layer are laminated in this order, have been proposed as packaging materials for use in electricity storage devices such as electric vehicles, hybrid electric vehicles, personal computers, cameras, mobile phones, etc. Furthermore, such film-like packaging materials for electricity storage devices are also being considered for use as packaging materials for electricity storage devices to be installed outdoors, such as stationary storage batteries (ESS: Energy Storage Systems).

[0008] Since outdoor power storage devices are installed outdoors, they are required to have a long service life of, for example, 10 years or more in high temperature and high humidity environments.

[0009] However, when an exterior packaging material for an electricity storage device, in which a base layer, an adhesive layer, a barrier layer, and a heat-sealable resin layer are laminated in this order, is placed in a high-temperature and high-humidity environment, the adhesive strength of the adhesive layer bonding the base layer and the barrier layer decreases, resulting in a problem in which the base layer and the barrier layer peel off.

[0010] In particular, such packaging materials for electricity storage devices are used as packaging materials for electricity storage devices by forming recesses by cold forming and accommodating electricity storage device elements in the spaces formed by the recesses. Therefore, they are required to have excellent moist heat resistance after cold forming. For example, although packaging materials intended for use in conventional in-vehicle and mobile device electricity storage devices are designed to have moist heat resistance, when they are intended for use in electricity storage devices installed outdoors, even higher moist heat resistance is required after cold forming. In conventional evaluation conditions for moist heat resistance, the evaluation temperature in an accelerated test is, for example, approximately 65°C to 85°C. The inventors of the present disclosure have considered the need to adopt stricter conditions for evaluating moist heat resistance in an accelerated test and evaluate durability in order to further extend the service life of electricity storage devices installed outdoors.

[0011] Under these circumstances, a main object of the present disclosure is to provide a cold-formable exterior packaging material for an electricity storage device that is composed of a laminate having at least a base layer, an adhesive layer, a barrier layer, and a heat-sealable resin layer in this order, and that has excellent moisture and heat resistance. [Means for solving the problem]

[0012] The present inventors have conducted extensive research to solve the above-mentioned problems, and as a result, have found that in a cold-formable packaging material for an electricity storage device that is composed of a laminate including at least a base layer, an adhesive layer, a barrier layer, and a heat-sealable resin layer in this order, by using an adhesive layer that has moisture and heat resistance for bonding between the base layer and the barrier layer, the packaging material for an electricity storage device can have excellent moisture and heat resistance.

[0013] 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. The laminate is composed of at least a base layer, an adhesive layer, a barrier layer, and a heat-sealable resin layer in this order, The adhesive layer has moisture and heat resistance, The laminate is a packaging material for an electricity storage device that can be cold-formed. [Effects of the Invention]

[0014] According to the present disclosure, it is possible to provide a cold-formable packaging material for an electricity storage device that is composed of a laminate including at least a base layer, an adhesive layer, a barrier layer, and a heat-sealable resin layer in this order, and that has excellent moisture and heat resistance. The present disclosure can also provide a method for manufacturing a packaging material for an electricity storage device, and an electricity storage device. [Brief explanation of the drawings]

[0015] [Figure 1] 1 is a schematic diagram showing an example of a cross-sectional structure of an exterior packaging material for an electricity storage device according to the present disclosure. [Figure 2]1 is a schematic diagram showing an example of a cross-sectional structure of an exterior packaging material for an electricity storage device according to the present disclosure. [Figure 3] 1 is a schematic diagram showing an example of a cross-sectional structure of an exterior packaging material for an electricity storage device according to the present disclosure. [Figure 4] 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. [Figure 5] FIG. 2 is a schematic diagram illustrating the directions in which the heat shrinkage rate and the wet heat shrinkage rate are measured. [Figure 6] FIG. 2 is a schematic diagram illustrating a method for preparing a test sample for evaluating moist heat resistance. [Figure 7] FIG. 2 is a schematic diagram for explaining a method for evaluating moist heat resistance. DETAILED DESCRIPTION OF THE INVENTION

[0016] The electrical storage device packaging material of the present disclosure is composed of a laminate including at least a substrate layer, an adhesive layer, a barrier layer, and a heat-sealable resin layer in this order, the adhesive layer having moisture and heat resistance, and the laminate being cold-formable. By having such a configuration, the electrical storage device packaging material of the present disclosure can provide a cold-formable electrical storage device packaging material including a laminate including at least a substrate layer, an adhesive layer, a barrier layer, and a heat-sealable resin layer in this order, and having excellent moisture and heat resistance.

[0017] The exterior packaging material for an electricity storage device of the present disclosure will be described in detail below. In this specification, a numerical range indicated by "to" means "greater than or equal to" or "less than or equal to." For example, the expression "2 to 15 mm" means 2 mm or more and 15 mm or less. In this specification, the thickness of each layer constituting the laminate is rounded to one decimal place.

[0018] 1.Layer structure and physical properties of exterior materials for energy storage devices As shown in FIG. 1 , for example, an electrical storage device packaging material 10 according to the present disclosure is composed of a laminate including at least a base material layer 1, an adhesive layer 2, a barrier layer 3, and a heat-sealable resin layer 4 in this order. In the electrical storage device packaging 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 electrical storage device using the electrical storage device packaging material 10 and an electrical storage device element, the electrical storage device element is housed in a space formed by heat-sealing the peripheral portions of the electrical storage device packaging material 10 with the heat-sealable resin layers 4 of the electrical storage device packaging material 10 facing each other. In the laminate constituting the electrical storage device packaging material 10 according to the present disclosure, with the barrier layer 3 as the reference, the heat-sealable resin layer 4 side relative to the barrier layer 3 is the inner side, and the base material layer 1 side relative to the barrier layer 3 is the outer side.

[0019] 2 and 3, the packaging material 10 for an electricity storage device may have an adhesive layer 5 between the barrier layer 3 and the heat-sealable resin layer 4, if necessary, for the purpose of improving the adhesion between these layers. Furthermore, as shown in FIG. 4, a surface coating layer 6 or the like may be provided on the outer side of the base material layer 1 (the side opposite to the heat-sealable resin layer 4 side), if necessary.

[0020] The thickness of the laminate constituting the electrical storage device packaging material 10 is not particularly limited, but from the viewpoints of cost reduction, improving 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 packaging material to protect the electrical storage device elements, the thickness of the laminate constituting the electrical storage device packaging 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 packaging 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.

[0021] In the packaging material 10 for an electricity storage device, the ratio of the total thickness of the base material layer 1, adhesive layer 2, barrier layer 3, adhesive layer 5 (if provided as needed), heat-sealable resin layer 4, and surface coating layer 6 (if provided as needed) to the thickness (total thickness) of the laminate constituting the packaging material 10 for an electricity storage device is preferably 90% or more, more preferably 95% or more, and even more preferably 98% or more. As a specific example, when the packaging material 10 for an electricity storage device 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 packaging material 10 for an electricity storage device is preferably 90% or more, more preferably 95% or more, and even more preferably 98% or more. Furthermore, even when the packaging material 10 for an electricity storage device 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 packaging material 10 for an electricity storage device can be, for example, 80% or more, preferably 90% or more, more preferably 95% or more, and even more preferably 98% or more.

[0022] In the packaging material for an electricity storage device, the MD (Machine Direction) and TD (Transverse Direction) of the barrier layer 3 described below can usually be determined during the manufacturing process. For example, when the barrier layer 3 is made of an aluminum alloy foil, linear streaks called rolling marks are formed on the surface of the aluminum alloy foil in the rolling direction (RD) of the aluminum alloy foil. Since the rolling marks extend along the rolling direction, the rolling direction of the aluminum alloy foil can be determined by observing the surface of the aluminum alloy foil. Furthermore, during the manufacturing process of a laminate, the MD of the laminate usually coincides with the RD of the aluminum alloy foil, so the MD of the laminate can be identified by observing the surface of the aluminum alloy foil and identifying the rolling direction (RD) of the aluminum alloy foil. Furthermore, since the TD of the laminate is perpendicular to the MD of the laminate, the TD of the laminate can also be identified.

[0023] Furthermore, when the MD of the electrical storage device packaging material cannot be identified due to the rolling marks on the aluminum alloy foil, it can be identified by the following method. The MD of the electrical storage device packaging material can be confirmed by observing the cross section of the heat-sealable resin layer of the electrical storage device packaging material using an electron microscope to confirm the sea-island structure, and determining the direction parallel to the cross section where the average diameter of the island shapes in the direction perpendicular to the thickness direction of the heat-sealable resin layer is the largest. Specifically, the sea-island structure can be confirmed by observing the longitudinal cross section of the heat-sealable resin layer and each cross section, angled 10 degrees from the direction parallel to the longitudinal cross section, up to the direction perpendicular to the longitudinal cross section (a total of 10 cross sections), using an electron microscope. Next, the shape of each individual island is observed in each cross section. For each island shape, the linear distance connecting the leftmost end in the direction perpendicular to the thickness direction of the heat-sealable resin layer to the rightmost end in the perpendicular direction is defined as the diameter y. For each cross section, the average of the diameters y of the top 20 island shapes in descending order of diameter y is calculated. The direction parallel to the cross section where the average diameter y of the island shape was the largest was determined to be the MD.

[0024] In the packaging material for an electricity storage device according to the present disclosure, the adhesive layer described below has moist heat resistance. Furthermore, the packaging material for an electricity storage device according to the present disclosure can be cold-formed.

[0025] Here, the adhesive layer 2 preferably has moist heat resistance under accelerated test conditions of a temperature of 120°C and a saturated steam environment (for example, a test time of 10 hours or more, as described below). More specifically, when the moist heat resistance evaluation method described below is used to check peeling between the base material layer 1 and the barrier layer 3 for the cold-formed electrical storage device packaging material 10, peeling preferably occurs in 4 or fewer test samples, more preferably 3 or fewer test samples, even more preferably 2 or fewer test samples, and particularly preferably 0 test samples. The moist heat resistance evaluation method described below corresponds to the evaluation method of leaving the samples in an autoclave for 10 hours in the moist heat resistance evaluation 3 (temperature 120°C, saturated steam environment) described later in the Examples.

[0026] (Method for evaluating humidity and heat resistance) The exterior material for an electricity storage device is prepared into a test sample that is rectangular in plan view, measuring 120 mm in the TD direction and 80 mm in the MD direction. The number of test samples is 12. Next, as cold forming molds, a male mold that is rectangular in plan view, measuring 54.5 mm in the TD direction and 31.6 mm in the MD direction, and a female mold with a clearance of 0.5 mm from the male mold are prepared. The surface of the ridgeline of the male mold has a maximum height roughness (nominal Rz value) of 1.6 μm as specified in Table 2 of the surface roughness standard for comparison in JIS B 0659-1:2002, Appendix 1 (Reference), and the surface other than the ridgeline has a maximum height roughness (nominal Rz value) of 3.2 μm, a corner curvature radius R of 2.0 mm, and a ridgeline curvature radius R of 1.0 mm as specified in Table 2 of the surface roughness standard for comparison in JIS B 0659-1:2002, Appendix 1 (Reference).The surface of the female mold has a maximum height roughness (nominal Rz value) of 3.2 μm, a corner curvature radius R of 2.0 mm, and a ridgeline curvature radius R of 1.0 mm as specified in Table 2 of the surface roughness standard for comparison in JIS B 0659-1:2002, Appendix 1 (Reference). The test sample is placed on the female mold with the heat-sealable resin layer facing the male mold. The test sample is then pressed with a surface pressure of 0.13 MPa and subjected to cold forming in a single step. (Note that the forming depth is appropriately adjusted within the range of 5.0 mm to 7.0 mm for evaluation. For example, the forming depth may be 5.0 mm, 5.5 mm, 6.0 mm, 6.5 mm, or 7.0 mm. For example, if the base layer is composed of a laminate of polyester film and polyamide film, the forming depth is 5.0 mm. For example, if the base layer is composed of a polyamide film, the forming depth is 7.0 mm.) The cold-formed test sample is then placed in an autoclave. The autoclave is set to a temperature of 120°C and saturated with steam, and the sample is left standing for 10 hours. The test sample is then removed from the autoclave, and the base layer and barrier layer are visually inspected to determine whether delamination has occurred between these layers. The location where delamination is most likely to occur is the corner of the test sample near the flange side of the molded recess (part d in Figure 7).At this location, stress is likely to be applied to each layer of the laminate due to cold forming, and the base layer 1 in particular is likely to undergo thermal shrinkage or wet heat shrinkage at this location. Therefore, if the adhesive layer 2 in contact with the base layer 1 does not have wet heat resistance, peeling will occur between the layers at this location.

[0027] Furthermore, in the above-described method for evaluating moist heat resistance, when the electrical storage device packaging material of the present disclosure is left in an autoclave for 12 hours, of a total of 12 test samples of the electrical storage device packaging material, preferably 4 or less test samples exhibit peeling, more preferably 3 or less test samples, even more preferably 2 or less test samples, and particularly preferably 0 test samples.

[0028] The electrical storage device packaging material 10 of the present disclosure preferably has a peel strength of 5.0 N / 15 mm or more at room temperature (25°C) as measured using the method of Heat Resistance Evaluation 1 described below. The higher the peel strength at room temperature (25°C), the better, but the upper limit, for example, is 12.0 N / 15 mm or less. The electrical storage device packaging material 10 of the present disclosure preferably has a peel strength of 3.0 N / 15 mm or more at 120°C as measured using the method of Heat Resistance Evaluation 1 described below. The higher the peel strength at 120°C, the better, but the upper limit, for example, is 8.0 N / 15 mm or less.

[0029] The ratio (%) of the peel strength at 120°C to the peel strength at room temperature is preferably 25% or more, more preferably 30% or more, even more preferably 40% or more, and particularly preferably 50% or more. The peel strength ratio is, for example, 90% or less, 80% or less, or 70% or less.

[0030] <Heat resistance evaluation 1> In accordance with the provisions of JIS K7127:1999, the peel strength of the electrical storage device packaging material is measured at room temperature (25°C) or 120°C as follows. A test sample is cut out from the electrical storage device packaging material into a strip shape with a width of 15 mm (TD direction) and a length of 150 mm (MD direction). The MD of the electrical storage device packaging material corresponds to the rolling direction (RD) of the aluminum alloy foil, and the TD of the electrical storage device packaging material corresponds to the TD of the aluminum alloy foil. Next, on one short side of the test sample, the side including the base layer and the side including the barrier layer are peeled at the interface between the adhesive layer and the barrier layer to an extent that they can be gripped with the gripping tools of a tensile tester (for example, AG-Xplus (trade name) manufactured by Shimadzu Corporation), to prepare a test sample for measurement. Next, the test sample for measurement is attached to a tensile tester and left at each measurement temperature for 2 minutes. Subsequently, the peel strength (N / 15 mm) between the base layer and the barrier layer is measured using the tensile tester under the conditions of 180° peel, tensile speed 50 mm / min, and gauge length 50 mm. The strength when the gauge length reaches 57 mm is defined as the peel strength (N / 15 mm). The peel strength (N / 15 mm) is measured three times, and the average value is evaluated as the peel strength (N / 15 mm) at each temperature.

[0031] Furthermore, the packaging material for an electricity storage device according to the present disclosure is preferably evaluated as having high heat resistance in the following heat resistance evaluation 2.

[0032] <Heat resistance evaluation 2> As in the <Moldability Evaluation> described below, each electrical storage device exterior material was cut into a rectangular shape measuring 90 mm in length (MD) × 160 mm in width (TD), and the test sample was cold-formed using the above-mentioned forming die. Next, as shown in the schematic diagram of Figure 6, the cold-formed test sample was folded at the position of dashed line P with the molding recess 21 of test sample 20 facing inward (so that the heat-sealable resin layers face each other) (Figures 6(a) and 6(b)). Next, two locations along the outer edge of the molding recess were heat-sealed in the TD and MD directions, respectively (Figure 6(c)). In Figure 6, the heat-sealed portion S1 in the TD direction and the heat-sealed portion S2 in the MD direction are indicated by hatched areas. The heat-sealing conditions were 190°C or 210°C, a surface pressure of 1.0 MPa, 3 seconds, and a seal width of 7 mm. After heat sealing, the test samples were visually inspected to see if there was any lifting between the base layer and the barrier layer (peeling of the base layer), and the percentage of test samples with lifting out of each of the 10 test samples was determined. If the percentage of test samples with lifting was in the range of 0 / 10 to 4 / 10, the heat resistance of the cold-formed exterior material for an electricity storage device was deemed to be high.

[0033] Furthermore, the limit forming depth of the electrical storage device packaging material of the present disclosure, when no lubricant is present on both sides, as measured by the following formability evaluation method, is preferably 4.0 mm or more, more preferably 5.0 mm or more. The limit forming depth is, for example, 10.0 mm or less. When a lubricant is present on both sides, the limit forming depth is preferably 5.0 mm or more, more preferably 6.0 mm or more. The limit forming depth is, for example, 12.0 mm or less.

[0034] <Moldability evaluation> For the electrical storage device packaging material, test samples (with lubricant) in which erucic acid amide was applied as a lubricant to both sides of the electrical storage device packaging material (the surface of the base material layer and the surface of the heat-sealable resin layer), and test samples (without lubricant) in which no lubricant was applied were prepared, and cold forming was performed under the following conditions. First, the electrical storage device packaging material was cut into a rectangle with a length (MD direction) of 90 mm and a width (TD direction) of 150 mm to prepare the test sample. The MD of the electrical storage device packaging material corresponds to the rolling direction (RD) of the aluminum alloy foil, and the TD of the electrical storage device packaging material corresponds to the TD of the aluminum alloy foil. Next, each test sample was placed in a 25°C environment in a rectangular molding die (female die, the surface of which had a maximum height roughness (nominal value of Rz) of 3.2 μm, a corner curvature radius R of 2.0 mm, and a ridgeline curvature radius R of 1.0 mm, as specified in Table 2 of JIS B 0659-1:2002, Annex 1 (Reference), Surface Roughness Standard Pieces for Comparison) with a diameter of 31.6 mm (MD) x 54.5 mm (TD). The corresponding molding die (male die, the surface of the ridgeline had a maximum height roughness (nominal value of Rz) of 1.6 μm, as specified in Table 2 of JIS B 0659-1:2002, Annex 1 (Reference), Surface Roughness Standard Pieces for Comparison, and the surface other than the ridgeline had a maximum height roughness (nominal value of Rz) of 1.6 μm, as specified in Table 2 of JIS B Using the maximum height roughness (nominal Rz value) of 3.2 μm, the corner curvature radius R of 2.0 mm, and the ridge curvature radius R of 1.0 mm specified in Table 2 of the reference surface roughness standard specimens in 0659-1:2002 Annex 1 (Reference), ten test samples were cold-formed (single-stage, drawn-in molding) at a pressing pressure (surface pressure) of 0.25 MPa and at various molding depths (5.0 mm to 8.5 mm). The test samples were placed on a female mold with the heat-sealable resin layer facing the male mold, and molding was performed at room temperature (25°C). The clearance between the male and female molds was 0.3 mm. For cold-formed exterior materials for electricity storage devices, the deepest forming depth at which no pinholes or cracks occur in the aluminum alloy foil in any of the 10 test samples is defined as A mm, and the number of test samples at the shallowest forming depth at which pinholes, etc. occur in the aluminum alloy foil is defined as B. The value calculated using the following formula is rounded to two decimal places to determine the limit forming depth of the exterior material for electricity storage devices. Limit forming depth = A mm + (0.5 mm / 10 pieces) x (10 pieces - B pieces)

[0035] Specifically, the phrase "the exterior material for an electricity storage device according to the present disclosure is cold-formable" means that the limit forming depth measured by the above-described formability evaluation method is 4.0 mm or more, more preferably 5.0 mm or more, when no lubricant is present on both sides. Furthermore, when lubricant is present on both sides, the limit forming depth is preferably 5.0 mm or more, more preferably 6.0 mm or more.

[0036] 2. Each layer that forms the exterior material for the energy storage device [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, etc. The substrate layer 1 is located on the outer layer side of the packaging material for an electricity storage device.

[0037] There are no particular limitations on the material forming the base layer 1, as long as it functions as a base, i.e., has at least insulating properties. The base layer 1 can be formed using, for example, a resin, which may contain additives described below.

[0038] When the base layer 1 is formed of a resin, the base layer 1 may be, for example, a resin film formed of a resin, or may be formed by applying a resin. The resin film may be an unstretched film or a stretched film. Examples of stretched films include uniaxially stretched films and biaxially stretched films, with biaxially stretched films being preferred. Examples of stretching methods for forming biaxially stretched films include sequential biaxial stretching, inflation, and simultaneous biaxial stretching. Examples of methods for applying a resin include roll coating, gravure coating, and extrusion coating.

[0039] 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. Furthermore, it may also be a mixture of these resins.

[0040] Of these, preferred resins for forming the base layer 1 include polyester and polyamide.

[0041] Specific examples of polyesters include polyethylene terephthalate, polybutylene terephthalate, polyethylene naphthalate, polybutylene naphthalate, polyethylene isophthalate, and copolymer polyesters. Examples of copolymer polyesters include copolymer polyesters in which ethylene terephthalate is the main repeating unit. Specific examples include copolymer polyesters in which ethylene terephthalate is the main repeating unit and is 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.

[0042] 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; and aromatic polyamides such as polyamide MXD6 (polymetaxylylene adipamide); alicyclic polyamides such as polyamide PACM6 (polybis(4-aminocyclohexyl)methane adipamide); polyamides copolymerized with a lactam component or an isocyanate component such as 4,4'-diphenylmethane diisocyanate; polyesteramide copolymers and polyetheresteramide copolymers, which are copolymers of copolymerized polyamides with polyesters or polyalkylene ether glycols; and polyamides such as copolymers of these. These polyamides may be used singly or in combination of two or more.

[0043] The base layer 1 preferably includes at least one of a polyester film, a polyamide film, and a polyolefin film, preferably includes at least one of a stretched polyester film, a stretched polyamide film, and a stretched polyolefin film, more preferably includes 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 includes 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.

[0044] The base material layer 1 may be a single layer, or may be composed of two or more layers. When the base material layer 1 is composed of two or more layers, the base material 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 material layer 1 without being stretched, or may be uniaxially or biaxially stretched to form the base material layer 1.

[0045] Specific examples of laminates of two or more resin films in the base layer 1 include a laminate of a polyester film and a nylon film, a laminate of two or more nylon films, and a laminate of two or more polyester films. Preferably, a laminate of a stretched nylon film and a stretched polyester film, a laminate of two or more stretched nylon films, or a laminate of two or more stretched polyester films is preferred. For example, when the base layer 1 is a laminate of two resin films, a laminate of a polyester resin film and a polyester resin film, a laminate of a polyamide resin film and a polyamide resin film, or a laminate of a polyester resin film and a polyamide resin film is preferred. A laminate of a polyethylene terephthalate film and a polyethylene terephthalate film, a laminate of a nylon film and a nylon film, or a laminate of a polyethylene terephthalate film and a nylon film is more preferred. Generally, polyester resin films tend to have lower heat shrinkage and moisture absorption than polyamide resin films. Therefore, by positioning the polyester resin film on the outer side of the polyamide film, the heat shrinkage and moisture absorption of the polyamide film can be suppressed. It is preferable to use a polyamide film for the base layer that satisfies the heat shrinkage rate and wet heat shrinkage rate described below. In addition, since polyester resins are less likely to discolor when an electrolyte solution adheres to their surface, when the base layer 1 is a laminate of two or more resin films, it is preferable that the polyester resin film be located as the outermost layer of the base layer 1.

[0046] When the base 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 the adhesive layer 2 described below (i.e., adhesives that have moist heat resistance after curing). 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, it is preferable to use a polyurethane adhesive as the adhesive. In this case, the thickness of the adhesive may be, for example, about 2 to 5 μm. Alternatively, an anchor coat layer may be formed on the resin film before lamination. Examples of the anchor coat layer include those similar to those exemplified for the adhesive layer 2 described below. In this case, the thickness of the anchor coat layer may be, for example, about 0.01 to 1.0 μm.

[0047] From the viewpoint of suitably improving the formability and moist heat resistance of the electrical storage device packaging material of the present disclosure, the heat shrinkage rate of the resin film contained in the base material layer is preferably 5.0% or less, more preferably 3.5% or less, and even more preferably 3.0% or less. From the viewpoint of suitably suppressing peeling between the base material layer 1 and the barrier layer 3 in a moist heat environment, it is preferred that the resin film having such a heat shrinkage rate be located closest to the barrier layer in the base material layer. Furthermore, from the viewpoint of suitably improving the formability and moist heat resistance of the electrical storage device packaging material of the present disclosure and suitably suppressing peeling between the base material layer 1 and the barrier layer 3 in a moist heat environment, it is preferred that the heat shrinkage rate be sufficient in four directions of the base material layer: MD, TD, 45° direction, and 135° direction. Furthermore, it is desirable that the heat shrinkage rates in these four directions be highly uniform. The heat shrinkage rate is preferably 5.0% or less in all four directions of the base layer 1, i.e., the MD direction, the TD direction, the 45° direction, and the 135° direction, preferably 3.5% or less, more preferably 3.0% or less, more preferably 2.5% or less, and even more preferably 2.0% or less. A lower heat shrinkage rate is preferable, but a lower limit, for example, is preferably 0.1% and more preferably 0%. The difference between the highest and lowest heat shrinkage rates in the four directions of the base layer 1, i.e., the MD direction, the TD direction, the 45° direction, and the 135° direction, is preferably 5.0% or less, preferably 3.5% or less, more preferably 3.0% or less, more preferably 2.5% or less, and even more preferably 2.0% or less. A lower difference in heat shrinkage rate is preferable, but a lower limit, for example, is preferably 0.1% and more preferably 0%. As shown in Figure 5, one direction along the MD is defined as the 0° direction, and one direction in the TD direction perpendicular to the MD is defined as the 90° direction, and the heat shrinkage rates are measured in the 45° and 135° directions. In measuring the heat shrinkage rate, the 0° direction and the 180° direction coincide. A resin film having such a heat shrinkage rate is preferably a polyamide film, more preferably a nylon film, and even more preferably a stretched nylon film.The method for measuring the thermal shrinkage rate of the base material layer is as follows.

[0048] (Method for measuring the thermal shrinkage rate of the base layer) Using a method conforming to the provisions of JIS Z 1714:2009, the base material layer is used as a test sample, and the heat shrinkage (MD direction, TD direction, 45° direction, 135° direction) is measured under conditions of a test temperature of 160°C and a heating time of 30 minutes. The average value measured for each of three test samples is taken as the heat shrinkage.

[0049] Furthermore, from the viewpoint of suitably improving the formability and moist heat resistance of the exterior material for an electricity storage device of the present disclosure, the moist heat shrinkage rate of the resin film contained in the base material layer is preferably 3.0% or less, more preferably 2.5% or less. Furthermore, the moist heat shrinkage rate is preferably sufficient in all four directions of the base material layer: MD, TD, 45°, and 135°. Furthermore, it is desirable that the moist heat shrinkage rates in these four directions are highly uniform. The moist heat shrinkage rate of the base material layer 1 in all four directions: MD, TD, 45°, and 135° is preferably 3.0% or less, more preferably 2.5% or less, more preferably 2.0% or less, more preferably 1.9% or less, and even more preferably 1.8% or less. A lower moist heat shrinkage rate is preferable, but a lower limit is preferably 0.1%, more preferably 0%. Furthermore, the difference between the highest and lowest wet heat shrinkage values ​​among the four directions of the base layer 1, i.e., MD, TD, 45°, and 135°, is preferably 3.5% or less, more preferably 2.0% or less, more preferably 1.5% or less, and even more preferably 1.2% or less. The lower the difference in wet heat shrinkage values, the better, and a lower limit, for example, is preferably 0.1%, more preferably 0%. Resin films having such wet heat shrinkage values ​​are preferably polyamide films, more preferably nylon films, and even more preferably stretched nylon films. The wet heat shrinkage of the base layer is measured as follows:

[0050] (Method for measuring wet heat shrinkage of base layer) Using a method conforming to the provisions of JIS Z 1714:2009, the substrate layer is used as a test sample and the wet heat shrinkage (MD, TD, 45° and 135° directions) is measured under conditions of a test temperature of 85°C, a relative humidity of 85%RH and a heating time of 2 hours. The wet heat shrinkage is the average value measured for each of three test samples.

[0051] Furthermore, additives such as lubricants, flame retardants, antiblocking agents, antioxidants, light stabilizers, tackifiers, and antistatic agents may be present on at least one of the surface and the interior of the base material layer 1. Only one type of additive may be used, or two or more types may be mixed and used.

[0052] 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, and N,N'-distearyl sebacic acid amide. Specific examples of unsaturated fatty acid bisamides include ethylene bisoleic acid amide, ethylene biserucic acid amide, hexamethylene bisoleic acid amide, N,N'-dioleyl adipamide, and N,N'-dioleyl sebacic acid amide. Specific examples of fatty acid ester amides include stearamidoethyl stearate. Specific examples of aromatic bisamides include m-xylylene bisstearic acid amide, m-xylylene bishydroxystearic acid amide, N,N'-distearyl isophthalic acid amide, etc. The lubricants may be used singly or in combination of two or more.

[0053] When a lubricant is present on the surface of the base layer 1, the amount of the lubricant is not particularly limited, but is preferably about 3 mg / m 2 or more, more preferably 4 to 15 mg / m 2 approximately, more preferably 5 to 14 mg / m 2 The degree of

[0054] The lubricant present on the surface of the base layer 1 may be a lubricant exuded from the resin that constitutes the base layer 1, or a lubricant applied to the surface of the base layer 1.

[0055] The thickness of the base layer 1 is not particularly limited as long as it functions as a base, but from the viewpoint of suitably improving formability and moist heat resistance, it is preferably about 3 μm or more, more preferably about 5 μm or more, even more preferably about 8 μm or more, and particularly preferably about 10 μm or more. From the same viewpoint, the thickness of the base layer 1 is preferably about 50 μm or less, more preferably about 40 μm or less, and even more preferably about 35 μm or less. Preferred thickness ranges for the base layer 1 include about 3 to 50 μm, about 3 to 40 μm, about 3 to 45 μm, about 3 to 35 μm, about 5 to 50 μm, about 5 to 40 μm, about 5 to 45 μm, about 5 to 35 μm, about 8 to 50 μm, about 8 to 40 μm, about 8 to 45 μm, about 8 to 35 μm, about 10 to 50 μm, about 10 to 40 μm, about 10 to 45 μm, and about 10 to 35 μm.

[0056] Furthermore, when the base layer 1 is a laminate of two or more resin film layers, the thickness of each resin film constituting each layer is preferably about 2 μm or more, more preferably about 3 μm or more, even more preferably about 6 μm or more, and particularly preferably about 8 μm or more. From the same viewpoint, the thickness of the base layer 1 is preferably about 30 μm or less, more preferably about 25 μm or less, and even more preferably about 20 μm or less. Preferred thickness ranges for the base layer 1 include about 2 to 30 μm, about 2 to 25 μm, about 2 to 20 μm, about 3 to 30 μm, about 3 to 25 μm, about 3 to 20 μm, about 6 to 30 μm, about 6 to 25 μm, about 6 to 20 μm, about 8 to 30 μm, about 8 to 25 μm, and about 8 to 20 μm.

[0057] In the packaging material for an electricity storage device of the present disclosure, a particularly preferred configuration of the base material layer 1 is one in which an outermost polyethylene terephthalate film (preferably having a thickness of about 8 to 20 μm) and a nylon film (preferably having a thickness of about 8 to 20 μm) are bonded together by an adhesive layer (preferably having a thickness of about 2 to 5 μm) formed from an adhesive such as the adhesive exemplified for adhesive layer 2 described below. In this configuration, the nylon film preferably has the above-mentioned heat shrinkage rate or wet heat shrinkage rate. Another particularly preferred configuration of the base material layer 1 is one in which the base material layer is composed of a single layer of nylon film (preferably having a thickness of 10 to 30 μm, more preferably 20 to 30 μm).

[0058] [Adhesive layer 2] In the packaging material for an electricity storage device of the present disclosure, the adhesive layer 2 is a layer provided between the base layer 1 and the barrier layer 3 for the purpose of increasing the adhesion between them.

[0059] The electrical storage device packaging material of the present disclosure is characterized in that it is cold-formable and that the adhesive layer 2 has moist heat resistance. As described above, the adhesive layer 2 having moist heat resistance preferably has moist heat resistance at a temperature of 120°C and in a saturated water vapor environment. More specifically, when peeling between the base material layer 1 and the barrier layer 3 is confirmed for the electrical storage device packaging material 10 after cold forming using the moist heat resistance evaluation method described above (leaving in an autoclave for 10 hours, or even 12 hours), the number of test samples in which peeling occurs is preferably 4 or less, more preferably 3 or less, even more preferably 2 or less, and particularly preferably 0, out of a total of 12 test samples of the electrical storage device packaging material.

[0060] From the viewpoint of suitably improving the formability and moist heat resistance of the packaging material for an electricity storage device of the present disclosure, the glass transition temperature of the adhesive layer 2 is preferably 40° C. or higher, more preferably 80° C. or higher, even more preferably 100° C. or higher, and even more preferably 111° C. or higher. From the same viewpoint, the glass transition temperature of the adhesive layer 2 is preferably 150° C. or lower, more preferably 145° C. or lower, even more preferably 139° C. or lower, and even more preferably 135° C. or lower. Preferred ranges for the glass transition temperature of the adhesive layer 2 are about 40 to 150° C., about 40 to 145° C., about 40 to 139° C., about 40 to 135° C., about 80 to 150° C., about 80 to 145° C., about 80 to 139° C., about 80 to 135° C., about 100 to 150° C., about 100 to 145° C., about 100 to 139° C., about 100 to 135° C., about 111 to 150° C., about 111 to 145° C., about 111 to 139° C., and about 111 to 135° C. The glass transition temperature of the adhesive layer 2 is measured by the following method.

[0061] <Method for measuring glass transition temperature> The glass transition temperature is measured using a differential scanning calorimeter (e.g., a differential scanning calorimeter Q200 manufactured by TA Instruments). Specifically, using differential scanning calorimetry (DSC) according to the procedure of JIS K7121:2012 (Method for measuring transition temperatures of plastics (JIS K7121:1987, Supplement 1)), the adhesive layer is held at 30°C for 10 minutes, then heated from 30°C to 200°C at a heating rate of 10°C / min. The glass transition temperature is determined by determining the temperature at the intersection of a line drawn from the low-temperature baseline to the high-temperature side and a tangent drawn at the point where the gradient of the step-like change in the glass transition curve is maximum. The adhesive layer used for the measurement was prepared by applying the adhesive used for adhesive layer 2 of the electrical storage device exterior material to a polyethylene terephthalate (PET) film (3 μm thick) and then aging the adhesive.

[0062] The adhesive layer 2 is formed from an adhesive capable of bonding the base material layer 1 and the barrier layer 3. The adhesive may be any of a chemical reaction type, a solvent volatilization type, a hot melt type, a hot pressure type, etc., as long as it can form an adhesive layer having moisture and heat resistance. 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.

[0063] Specific examples of adhesive components contained in the adhesive 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-based 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 component resins can be increased by using an appropriate curing agent in combination. The curing agent is selected appropriately from polyisocyanates, multifunctional epoxy resins, oxazoline group-containing polymers, polyamine resins, acid anhydrides, and the like, depending on the functional groups of the adhesive components.

[0064] Examples of polyurethane adhesives include polyurethane adhesives containing a first part containing a polyol compound and a second part containing an isocyanate compound. Two-component curing polyurethane adhesives are preferred, with a first part containing a polyol such as polyester polyol, polyether polyol, or acrylic polyol, and a second part containing an aromatic or aliphatic polyisocyanate. Examples of polyurethane adhesives include polyurethane adhesives containing a polyurethane compound obtained by reacting a polyol compound with an isocyanate compound in advance, and an isocyanate compound. Examples of polyurethane adhesives include polyurethane adhesives containing a polyurethane compound obtained by reacting a polyol compound with an isocyanate compound in advance, and a polyol compound. Examples of polyurethane adhesives include polyurethane adhesives obtained by reacting a polyurethane compound obtained by reacting a polyol compound with an isocyanate compound in advance with moisture, such as in the air, and curing the polyurethane compound. Polyol compounds preferably include polyester polyols having hydroxyl groups on the side chains in addition to terminal hydroxyl groups in the repeating units. 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). Other examples include polyfunctional isocyanate-modified products 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 the side surface is coated with an electrolyte.

[0065] When the adhesive layer 2 is formed from a cured product of a two-component polyurethane adhesive, the glass transition temperature of the adhesive layer 2 preferably satisfies the above-mentioned glass transition temperature of the adhesive layer 2. That is, the glass transition temperature of the adhesive layer 2 formed from a cured product of a two-component polyurethane adhesive is preferably 40°C or higher, more preferably 80°C or higher, even more preferably 100°C or higher, and even more preferably 111°C or higher. From the same viewpoint, the glass transition temperature of the adhesive layer 2 is preferably 150°C or lower, more preferably 145°C or lower, even more preferably 139°C or lower, and even more preferably 135°C or lower. Preferred ranges for the glass transition temperature of the adhesive layer 2 are approximately 40 to 150°C, approximately 40 to 145°C, approximately 40 to 139°C, approximately 40 to 135°C, approximately 80 to 150°C, approximately 80 to 145°C, approximately 80 to 139°C, approximately 80 to 135°C, approximately 100 to 150°C, approximately 100 to 145°C, approximately 100 to 139°C, approximately 100 to 135°C, approximately 111 to 150°C, approximately 111 to 145°C, approximately 111 to 139°C, and approximately 111 to 135°C.

[0066] In the electrical storage device exterior material of the present disclosure, the adhesive forming the adhesive layer 2 is preferably a two-component polyurethane adhesive. In order for the two-component polyurethane adhesive to be cold-formable after curing and to exhibit high moist heat resistance, it is designed to suppress hydrolysis of the polyurethane after curing and to have a highly flexible chemical structure. For example, to suppress hydrolysis of the polyurethane, the cohesive strength after curing is increased and a compound containing a substituent that reacts with acid, such as a carbodiimide group or an epoxy group, is added. Furthermore, to increase the flexibility of the polyurethane, for example, the ratio of soft segments to hard segments contained in the polyol compound is adjusted. When the adhesive layer 2 is formed from a cured product of a two-component polyurethane adhesive, the polyol compound forming the adhesive layer 2 preferably contains a basic acid component and a polyhydric alcohol component, and the basic acid component preferably contains a soft segment and a hard segment. Examples of soft segments include isophthalic acid and its derivatives, and examples of hard segments include terephthalic acid and its derivatives. Furthermore, to increase the flexibility of the adhesive layer 2, the mass ratio (soft segment:hard segment) of the soft segment (e.g., isophthalic acid and its derivatives) to the hard segment (e.g., terephthalic acid and its derivatives) is preferably, for example, about 35:65 to 90:10, and more preferably about 40:60 to 85:15. To increase the moist heat resistance of the polyurethane after curing, it is desirable to reduce the catalyst residue contained in the two-component polyurethane adhesive and slow the hydrolysis rate of the polyurethane. Furthermore, it is preferable to adjust the glass transition temperature of the two-component polyurethane adhesive after curing.

[0067] Furthermore, the adhesive layer 2 may contain other components as long as they do not impair adhesion, moldability, or moist heat resistance, and may contain colorants, thermoplastic elastomers, tackifiers, fillers, and the like. By including a colorant in the adhesive layer 2, the electrical storage device packaging material 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.

[0068] The type of pigment is not particularly limited as long as it does not impair the adhesiveness 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, while examples of inorganic pigments include carbon black-based, titanium oxide-based, cadmium-based, lead-based, chromium oxide-based, and iron-based pigments, and other examples include finely powdered mica and fish scale foil.

[0069] Among colorants, carbon black is preferred in order to give the exterior appearance of the electrical storage device packaging material a black color, for example.

[0070] The average particle size of the pigment is not particularly limited and may be, for example, about 0.05 to 5 μm, and preferably about 0.08 to 2 μm. The average particle size of the pigment is the median size measured with a laser diffraction / scattering particle size distribution measuring device.

[0071] The content of the pigment in the adhesive layer 2 is not particularly limited as long as it colors the packaging material for an electricity storage device, and may be, for example, about 5 to 60 mass %, and preferably 10 to 40 mass %.

[0072] 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, about 1 μm or more, or about 2 μm or more. The thickness of the adhesive layer 2 is, for example, about 10 μm or less, or about 5 μm or less. Preferred ranges for the thickness of the adhesive layer 2 include about 1 to 10 μm, about 1 to 5 μm, about 2 to 10 μm, and about 2 to 5 μm.

[0073] [Colored layer] The colored layer is a layer (not shown) that is provided between the base material layer 1 and the barrier layer 3 as needed. 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. Alternatively, a colored layer may 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.

[0074] 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 the colorant. Furthermore, only one type of colorant may be used, or two or more types may be mixed together.

[0075] Specific examples of the colorant contained in the colored layer include the same as those exemplified in the section [Adhesive layer 2].

[0076] [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.

[0077] Examples of the barrier layer 3 include metal foils, vapor-deposited films, and resin layers having 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 mainly composed of chlorotrifluoroethylene (CTFE), polymers mainly composed of tetrafluoroethylene (TFE), polymers having fluoroalkyl groups, and polymers mainly composed of 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 constituting 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.

[0078] From the viewpoint of improving the formability of the electrical storage device packaging 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, an iron-containing aluminum alloy foil is preferred. In the iron-containing aluminum alloy foil (100% by mass), the iron content is preferably 0.1 to 9.0% by mass, more preferably 0.5 to 2.0% by mass. By setting the iron content to 0.1% by mass or more, an electrical storage device packaging material with better formability can be obtained. By setting the iron content to 9.0% by mass or less, an electrical storage device packaging material with better flexibility can be obtained. Examples of soft aluminum alloy foils include aluminum alloy foils having a composition 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 be added as needed. Softening can be achieved by annealing or other methods.

[0079] Examples of stainless steel foil include austenitic, ferritic, austenitic-ferritic, martensitic, and precipitation hardened stainless steel foils. From the viewpoint of providing an exterior material for an electricity storage device that has excellent formability, the stainless steel foil is preferably made of austenitic stainless steel.

[0080] Specific examples of austenitic stainless steels that can be used to form the stainless steel foil include SUS304, SUS301, and SUS316L, with SUS304 being particularly preferred.

[0081] In the case of a metal foil, the thickness of the barrier layer 3 should be sufficient to at least function as a barrier layer that prevents moisture penetration, and is, 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 an aluminum alloy foil, the above-mentioned range is particularly preferred. Furthermore, particularly when the barrier layer 3 is made of a 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. Furthermore, the thickness of the stainless steel foil is preferably about 10 μm or more, more preferably about 15 μm or more. Furthermore, preferred ranges for the thickness of the stainless steel foil include about 10 to 60 μm, about 10 to 50 μm, about 10 to 40 μm, about 10 to 30 μm, about 10 to 25 μm, about 15 to 60 μm, about 15 to 50 μm, about 15 to 40 μm, about 15 to 30 μm, and about 15 to 25 μm.

[0082] Furthermore, when the barrier layer 3 is a metal foil, it is preferable that a corrosion-resistant coating be provided on at least the surface opposite the substrate layer to prevent dissolution and corrosion. The barrier layer 3 may be provided with a corrosion-resistant coating on both sides. Here, the corrosion-resistant coating refers to a thin film formed on the surface of the barrier layer by, for example, a hydrothermal conversion treatment such as boehmite treatment, a chemical conversion treatment, anodizing treatment, a nickel or chromium plating treatment, or a corrosion prevention treatment such as applying a coating agent, to provide the barrier layer with corrosion resistance (e.g., acid resistance, alkali resistance, etc.). Specifically, the corrosion-resistant coating refers to a coating that improves the acid resistance of the barrier layer (acid-resistant coating) or a coating that improves the alkali resistance of the barrier layer (alkali-resistant coating). The corrosion-resistant coating may be formed by one type of treatment or a combination of two or more types. Furthermore, not only one layer but also multiple layers can be formed. Furthermore, among these treatments, the hydrothermal conversion treatment and anodizing treatment are treatments that dissolve the metal foil surface with a treatment agent to form a metal compound with excellent corrosion resistance. These treatments may be included in the definition of chemical conversion treatment. In addition, when the barrier layer 3 is provided with a corrosion-resistant coating, the barrier layer 3 includes the corrosion-resistant coating.

[0083] The corrosion-resistant coating prevents delamination between the barrier layer (e.g., aluminum alloy foil) and the substrate layer during molding of the exterior packaging material for an electricity storage device, prevents dissolution and corrosion of the barrier layer surface due to hydrogen fluoride produced by the reaction between the electrolyte and water, and in particular prevents dissolution and corrosion of aluminum oxide present on the barrier layer surface when the barrier layer is an aluminum alloy foil, and also improves the adhesion (wettability) of the barrier layer surface, thereby preventing delamination between the substrate layer and the barrier layer during heat sealing and between the substrate layer and the barrier layer during molding.

[0084] Various corrosion-resistant coatings formed by chemical conversion treatments are known, including corrosion-resistant coatings 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. Examples of 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. Examples of phosphorus compounds used in these treatments include sodium phosphate, potassium phosphate, ammonium phosphate, and polyphosphoric acid. Examples of 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 primarily composed of a metal phosphate such as Cr (chromium) phosphate, Ti (titanium) phosphate, Zr (zirconium) phosphate, or Zn (zinc) phosphate, or a mixture of these metal salts, or a treatment solution primarily composed of a nonmetallic phosphate and a mixture of these nonmetallic salts, or a mixture of these with a synthetic resin, using 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 be a polymer such as a phenolic resin or an acrylic resin, or may be a chromate treatment using an aminated phenol polymer having repeating units represented by the following general formulas (1) to (4): In the aminated phenol polymer, the repeating units represented by the following general formulas (1) to (4) may be contained alone or in any combination of two or more types.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. A derivative of polyacrylic acid, such as an ammonium salt, a sodium salt, or an amine salt of polyacrylic acid, is particularly preferred. In the present 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, or 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 and used.

[0085] [ka]

[0086] [ka]

[0087] [ka]

[0088] [ka]

[0089] In the 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. 1 and R 2 are the same or different and represent a hydroxy group, an alkyl group, or a hydroxyalkyl group. 1 and R 2Examples of the alkyl group represented by X and R include linear or branched alkyl groups having 1 to 4 carbon atoms, such as methyl, ethyl, n-propyl, isopropyl, n-butyl, isobutyl, and tert-butyl. 1 and R 2 Examples of the hydroxyalkyl group represented by the formula (1) include a linear or branched alkyl group having 1 to 4 carbon atoms 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. 1 and R 2 The alkyl group and hydroxyalkyl group represented by the formula (1) may be the same or different. In the 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 the formulas (1) to (4) is preferably about 500 to 1,000,000, and more preferably about 1,000 to 20,000. The aminated phenol polymer can be prepared, for example, by polycondensing a phenol compound or a naphthol compound with formaldehyde to produce a polymer comprising repeating units represented by the formula (1) or (3), and then polycondensing the polymer with formaldehyde and an amine (R 1 R 2 NH) to the functional group (-CHNR 1 R 2 The aminated phenol polymers can be used singly or in combination of two or more.

[0090] Another example of a corrosion-resistant coating is a thin film formed by a coating-type corrosion prevention treatment in which a coating agent containing at least one selected from the group consisting of a rare earth element oxide sol, an anionic polymer, and a cationic polymer is applied. The coating agent may further contain phosphoric acid or a phosphate salt, and a crosslinking agent for crosslinking the polymer. The rare earth element oxide sol has 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 from the perspective of further improving adhesion. The rare earth element oxide contained in the corrosion-resistant coating can be used alone or in combination of two or more. The liquid dispersion medium for the rare earth element oxide sol can be 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 composed 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 a compound having a functional group selected from an isocyanate group, a glycidyl group, a carboxyl group, and an oxazoline group, and a silane coupling agent. The phosphoric acid or phosphoric acid salt is preferably a condensed phosphoric acid or a condensed phosphate salt.

[0091] An 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 a barrier layer and baking the coating at 150°C or higher.

[0092] The corrosion-resistant coating may have a laminated structure, if necessary, by further laminating at least one of a cationic polymer and an anionic polymer, such as those mentioned above.

[0093] The composition of the corrosion-resistant film can be analyzed using, for example, time-of-flight secondary ion mass spectrometry.

[0094] The amount of the corrosion-resistant film formed on the surface of the barrier layer 3 in the chemical conversion treatment is not particularly limited. For example, in the case of applying chromate treatment, the amount of the corrosion-resistant film formed on the surface of the barrier layer 3 is 2 It is desirable that the chromate compound is contained in an amount, in terms of chromium, of about 0.5 to 50 mg, preferably about 1.0 to 40 mg, the phosphorus compound in terms of phosphorus, and the aminated phenol polymer in an amount, in terms of phosphorus, of about 1.0 to 200 mg, preferably about 5.0 to 150 mg, per unit area.

[0095] 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 adhesive strength with the barrier layer or 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 can reveal the thickness of the corrosion-resistant coating, for example, by measuring the thickness of the coating with secondary ions consisting of Ce, P, and O (e.g., Ce2PO4 + , CePO4 - At least one of the following ions may be present: Cr, P, and O secondary ions (e.g., CrPO2 + , CrPO4 - Peaks derived from at least one of the above are detected.

[0096] The chemical conversion treatment is carried out by applying a solution containing a compound used to form a corrosion-resistant coating to the surface of the barrier layer by bar coating, roll coating, gravure coating, immersion, or other methods, and then heating the barrier layer to a temperature of approximately 70 to 200°C. Furthermore, before applying the chemical conversion treatment to the barrier layer, the barrier layer may be subjected to a degreasing treatment using an alkali immersion method, electrolytic cleaning, acid cleaning, electrolytic acid cleaning, or other methods. By performing such a degreasing treatment, the chemical conversion treatment of the surface of the barrier layer can be carried out more efficiently. Furthermore, using an acid degreasing agent prepared by dissolving a fluorine-containing compound in an inorganic acid for the degreasing treatment not only degreases the metal foil but also forms a passive metal fluoride. In such cases, only the degreasing treatment may be performed.

[0097] [Thermal adhesive resin layer 4] In the 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 together when the electricity storage device is assembled.

[0098] 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 polyolefin and acid-modified polyolefin, are preferred. The presence of a polyolefin skeleton in the resin constituting the heat-sealable resin layer 4 can be determined by, for example, infrared spectroscopy, gas chromatography mass spectrometry, or the like. Furthermore, when the resin constituting the heat-sealable resin layer 4 is analyzed by infrared spectroscopy, a peak derived from maleic anhydride is preferably detected. For example, when maleic anhydride-modified polyolefin is measured by infrared spectroscopy, a peak derived from maleic anhydride is detected at a wavenumber of 1760 cm. -1 Near and wave number 1780cm -1 A peak derived from maleic anhydride is detected around . When the thermally adhesive resin layer 4 is a layer made of maleic anhydride-modified polyolefin, a peak derived from maleic anhydride is detected when measured by infrared spectroscopy. However, if the degree of acid modification is low, the peak becomes small and may not be detected. In such cases, analysis can be performed by nuclear magnetic resonance spectroscopy.

[0099] 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. Among 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.

[0100] The polyolefin may also be a cyclic polyolefin. Cyclic polyolefins are copolymers of olefins and cyclic monomers, and examples of olefins constituting the cyclic polyolefin include ethylene, propylene, 4-methyl-1-pentene, styrene, butadiene, and isoprene. Examples of cyclic monomers constituting the cyclic polyolefin include cyclic alkenes such as norbornene; and cyclic dienes such as cyclopentadiene, dicyclopentadiene, cyclohexadiene, and norbornadiene. Among these, preferred are cyclic alkenes, and more preferred are norbornene.

[0101] Acid-modified polyolefins are polymers modified by block polymerization or graft polymerization of polyolefins with an acid component. Examples of acid-modified polyolefins include the above-mentioned polyolefins, copolymers of the above-mentioned polyolefins with polar molecules such as acrylic acid or methacrylic acid, and crosslinked polyolefins. Examples of acid components used for acid modification include carboxylic acids or anhydrides thereof, such as maleic acid, acrylic acid, itaconic acid, crotonic acid, maleic anhydride, and itaconic anhydride.

[0102] The acid-modified polyolefin may be an acid-modified cyclic polyolefin. The acid-modified cyclic polyolefin is a polymer obtained by copolymerizing a part of the monomers constituting the cyclic polyolefin by replacing it with an acid component, or by block polymerizing or graft polymerizing an acid component onto the 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 for the modification of the polyolefin.

[0103] Preferred acid-modified polyolefins include polyolefins modified with carboxylic acid or its anhydride, polypropylenes modified with carboxylic acid or its anhydride, maleic anhydride-modified polyolefins, and maleic anhydride-modified polypropylenes.

[0104] The thermally adhesive resin layer 4 may be formed of one type of resin alone or may be formed of a blend polymer of two or more types of resins. Furthermore, the thermally adhesive resin layer 4 may be formed of only one layer, or may be formed of two or more layers of the same or different resins.

[0105] Furthermore, the heat-sealable resin layer 4 may contain a lubricant, etc., as necessary. When the heat-sealable resin layer 4 contains a lubricant, the moldability of the electrical storage device packaging material can be improved. The lubricant is not particularly limited, and known lubricants can be used. The lubricants may be used alone or in combination of two or more.

[0106] The lubricant is not particularly limited, but preferably an amide-based lubricant is used. Specific examples of the lubricant include those exemplified for the base layer 1. The lubricant may be used alone or in combination of two or more.

[0107] When a lubricant is present on the surface of the heat-sealable resin layer 4, the amount of the lubricant is not particularly limited. However, from the viewpoint of improving the formability of the packaging material for an electricity storage device, the amount of the lubricant is preferably 10 to 50 mg / m 2 approximately, more preferably 15 to 40 mg / m 2 The degree of

[0108] The lubricant present on the surface of the heat-sealable resin layer 4 may be a lubricant exuded from the resin constituting the heat-sealable resin layer 4, or a lubricant applied to the surface of the heat-sealable resin layer 4.

[0109] The thickness of the heat-sealable resin layer 4 is not particularly limited as long as it can heat-seal the heat-sealable resin layers to each other and function to seal the electricity storage device element, but may be, for example, about 100 μm or less, preferably about 85 μm or less, and more preferably about 15 to 85 μm. For example, when the thickness of the adhesive layer 5 described below is 10 μm or more, the thickness of the heat-sealable resin layer 4 is preferably about 85 μm or less, and more preferably about 15 to 45 μm. For example, when the thickness of the adhesive layer 5 described below is less than 10 μm or when the adhesive layer 5 is not provided, the thickness of the heat-sealable resin layer 4 is preferably about 20 μm or more, and more preferably about 35 to 85 μm.

[0110] [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 corrosion-resistant film) and the heat-sealable resin layer 4 in order to firmly bond them together.

[0111] The adhesive layer 5 is formed of 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. From the viewpoint 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. From the viewpoint 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 anhydrides thereof, acrylic acid, and methacrylic acid. However, from the viewpoints of ease of modification and versatility, maleic anhydride is most preferred. From the viewpoint of the heat resistance of the electrical storage device exterior material, the olefin component is preferably a polypropylene-based resin, and the adhesive layer 5 most preferably contains maleic anhydride-modified polypropylene.

[0112] The presence 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, and the analysis method is not particularly limited. Furthermore, the presence of an acid-modified polyolefin in the resin constituting the adhesive layer 5 can be determined by, for example, measuring a maleic anhydride-modified polyolefin by infrared spectroscopy, and finding a peak at a wave number of 1760 cm -1 Near and wave number 1780cm -1 A peak derived from maleic anhydride is detected around this point. However, if the degree of acid modification is low, the peak may be small and not be detected. In this case, analysis can be performed using nuclear magnetic resonance spectroscopy.

[0113] Furthermore, from the viewpoint of ensuring durability such as heat resistance and resistance to contents of the packaging material for an electricity storage device, and of ensuring moldability while reducing the thickness, the adhesive layer 5 is more preferably a cured product of a resin composition containing an acid-modified polyolefin and a curing agent. Preferred examples of the acid-modified polyolefin include those mentioned above.

[0114] The adhesive layer 5 is preferably a cured product of a resin composition containing an acid-modified polyolefin and at least one 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 selected from the group consisting of a compound having an isocyanate group and a compound having an epoxy group. The adhesive layer 5 preferably contains at least one selected from the group consisting of polyurethane, polyester, and epoxy resin, and more preferably contains polyurethane and epoxy resin. Examples of polyesters include 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 components of a curing agent such as a compound having an isocyanate group, a compound having an oxazoline group, or an epoxy resin remain in the adhesive layer 5, the presence of the unreacted components 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), and the like.

[0115] Furthermore, from the viewpoint of further enhancing 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 COC 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 COC 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.

[0116] The compound having an isocyanate group is not particularly limited, but from the viewpoint of effectively improving the adhesion between the barrier layer 3 and the adhesive layer 5, a polyfunctional isocyanate compound is preferably used. The polyfunctional isocyanate compound is not particularly limited as long as it is a compound having 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.

[0117] The content of the compound having an isocyanate 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 constituting the adhesive layer 5. This can effectively improve the adhesion between the barrier layer 3 and the adhesive layer 5.

[0118] The compound having an oxazoline group is not particularly limited as long as it is a compound having an oxazoline skeleton. Specific examples of the compound having an oxazoline group include those having a polystyrene main chain and those having an acrylic main chain. Examples of commercially available products include the Epocross series manufactured by Nippon Shokubai Co., Ltd.

[0119] 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 %, in the resin composition constituting the adhesive layer 5. This can effectively improve the adhesion between the barrier layer 3 and the adhesive layer 5.

[0120] An example of a compound having an epoxy group is an epoxy resin. The epoxy resin is not particularly limited as long as it is a resin capable of forming a crosslinked structure by 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 about 50 to 2,000, more preferably about 100 to 1,000, and even more preferably about 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.

[0121] 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, polyglycerin polyglycidyl ether, etc. One type of epoxy resin may be used alone, or two or more types may be used in combination.

[0122] The proportion of the epoxy resin 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 constituting the adhesive layer 5. This can effectively improve the adhesion between the barrier layer 3 and the adhesive layer 5.

[0123] 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 two-component curing polyurethane.

[0124] The proportion of polyurethane in 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 constituting adhesive layer 5. This effectively improves the adhesion between barrier layer 3 and adhesive layer 5 in an atmosphere containing components that induce corrosion of the barrier layer, such as an electrolyte solution.

[0125] In addition, when the 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 main agent, 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.

[0126] The adhesive layer 5 may contain a modifier having a carbodiimide group.

[0127] The thickness of the adhesive layer 5 is preferably about 50 μm or less, about 40 μm or less, about 30 μm or less, about 20 μm or less, or about 5 μm or less. The thickness of the adhesive layer 5 is preferably about 0.1 μm or more, or about 0.5 μm or more. The thickness of the adhesive layer 5 is preferably about 0.1 to 50 μm, about 0.1 to 40 μm, about 0.1 to 30 μm, about 0.1 to 20 μm, about 0.1 to 5 μm, about 0.5 to 50 μm, about 0.5 to 40 μm, about 0.5 to 30 μm, about 0.5 to 20 μm, or about 0.5 to 5 μm. More specifically, in the case of adhesives such as those exemplified for the adhesive layer 2 or a cured product of an acid-modified polyolefin and a curing agent, the thickness is preferably about 1 to 10 μm, and more preferably about 1 to 5 μm. Furthermore, when a resin exemplified for the heat-fusible resin layer 4 is used, the thickness is preferably about 2 to 50 μm, 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 a resin exemplified for the heat-fusible resin layer 4 is used, the heat-fusible resin layer 4 and the adhesive layer 5 can be formed, for example, by extrusion molding.

[0128] [Surface coating layer 6] The packaging material for an electricity storage device according to the present disclosure may have a surface coating layer 6 on the substrate layer 1 (the side of the substrate layer 1 opposite to the barrier layer 3) as needed, 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.

[0129] The surface coating layer 6 can be formed from a resin such as polyvinylidene chloride, polyester, polyurethane, acrylic resin, or epoxy resin.

[0130] 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. Among these, two-component curable polyurethane is preferred.

[0131] Examples of two-component curing polyurethanes include polyurethanes containing a first component containing a polyol compound and a second component containing an isocyanate compound. Preferred examples of two-component curing polyurethanes include those containing a polyol, such as polyester polyol, polyether polyol, or acrylic polyol, as the first component and an aromatic or aliphatic polyisocyanate as the second component. Examples of polyurethanes include polyurethane compounds prepared by reacting a polyol compound with an isocyanate compound in advance, and polyurethanes containing an isocyanate compound. Examples of polyurethanes include polyurethane compounds prepared by reacting a polyol compound with an isocyanate compound in advance, and polyurethanes containing a polyol compound. Examples of polyurethanes include polyurethanes prepared by reacting a polyol compound with an isocyanate compound in advance and curing the polyurethane compound with moisture, such as in the air. Polyol compounds preferably include polyester polyols having hydroxyl groups on the side chains in addition to terminal hydroxyl groups in the repeating units. Examples of the second component 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. It should be noted that an aliphatic isocyanate compound refers to an isocyanate that has an aliphatic group but does not have an 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.The surface coating layer 6 is formed from polyurethane, and thus the exterior packaging material for an electricity storage device is endowed with excellent resistance to an electrolyte solution.

[0132] The surface coating layer 6 may contain additives such as the aforementioned lubricants, antiblocking agents, matting agents, 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 imparted to the surface of the surface coating layer 6. 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 with a laser diffraction / scattering particle size distribution analyzer.

[0133] The additive may be either inorganic or organic. The shape of the additive is not particularly limited, and examples thereof include spherical, fibrous, plate-like, amorphous, and scaly shapes.

[0134] 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, crosslinked acrylic, crosslinked styrene, crosslinked polyethylene, benzoguanamine, gold, aluminum, copper, and nickel. The 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 viewpoints of dispersion stability, cost, and the like. The additives may also be subjected to various surface treatments, such as insulation treatment and high-dispersibility treatment.

[0135] The method for forming the surface coating layer 6 is not particularly limited, and examples thereof include a method of applying a resin to form the surface coating layer 6. When an additive is blended into the surface coating layer 6, a resin mixed with the additive may be applied.

[0136] The thickness of the surface coating layer 6 is not particularly limited as long as the surface coating layer 6 exhibits the above-mentioned functions, and may be, for example, about 0.5 to 10 μm, and preferably about 1 to 5 μm.

[0137] 3. Manufacturing method for exterior materials for power storage devices The method for producing an electrical storage device packaging material is not particularly limited as long as it can produce a laminate in which the layers of the electrical storage device packaging material of the present invention are laminated, and examples include a method comprising a step of laminating at least a base material layer 1, an adhesive layer 2, a barrier layer 3, and a heat-sealable resin layer 4 in this order. That is, this is a method for producing an electrical storage device packaging material that comprises a step of laminating at least a base material layer, an adhesive layer, a barrier layer, and a heat-sealable resin layer in this order to produce a laminate, in which the adhesive layer has moist heat resistance and the laminate is cold-formable.

[0138] An example of a method for producing an exterior packaging 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 base 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 an adhesive used to form adhesive layer 2 is applied to base layer 1 or to barrier layer 3 whose surface has been chemically treated as necessary, by a coating method such as gravure coating or roll coating, and then dried, and then the barrier layer 3 or base layer 1 is laminated thereon, and the adhesive layer 2 is cured.

[0139] 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. 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 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 laminating this on 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 previously 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 on the barrier layer 3 of the laminate A, followed by drying or baking, and then the heat-sealable resin layer 4 previously formed into a sheet is laminated on the adhesive layer 5.

[0140] When the surface coating layer 6 is provided, the surface coating layer 6 is laminated on the surface of the base material layer 1 opposite to the barrier layer 3. The surface coating layer 6 can be formed, for example, by applying the above-mentioned resin for forming the surface coating layer 6 to the surface of the base material layer 1. The order of the step of laminating the barrier layer 3 on the surface of the base material layer 1 and the step of laminating the surface coating layer 6 on the surface of the base material layer 1 is not particularly limited. For example, after the surface coating layer 6 is formed on the surface of the base material layer 1, the barrier layer 3 may be formed on the surface of the base material layer 1 opposite to the surface coating layer 6.

[0141] As described above, a laminate is formed which includes an optional surface coating layer 6, a substrate layer 1, an adhesive layer 2, a barrier layer 3, an optional adhesive layer 5, and a heat-sealable resin layer 4 in this order. In order to strengthen the adhesion of the adhesive layer 2 and the adhesive layer 5, the laminate may be further subjected to a heat treatment.

[0142] 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, ozone treatment, etc., as needed to improve processability. For example, by subjecting the surface of the base layer 1 opposite to the barrier layer 3 to corona treatment, the printability of ink on the surface of the base layer 1 can be improved.

[0143] 4. Applications of exterior materials for energy storage devices The exterior packaging 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 packaging material for an electricity storage device according to the present disclosure.

[0144] Specifically, an electricity storage device using the electricity storage device packaging material is provided by covering an electricity storage device element having at least a positive electrode, a negative electrode, and an electrolyte with the electricity storage device packaging material of the present disclosure in a state in which metal terminals connected to each of the positive electrode and the negative electrode protrude outward, so that a flange portion (a region where the heat-sealable resin layers contact each other) can be formed around the periphery of the electricity storage device element, and heat-sealing the heat-sealable resin layers of the flange portion to form a hermetic seal. Note that 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 inside (the surface in contact with 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 portions of the overlapped electrical storage device exterior packaging materials. Alternatively, as shown in the example of FIG. 4, one electrical storage device exterior packaging material may be folded back and overlapped, and the peripheral portions may be heat-sealed to form a package. When folding back and overlapping, as shown in the example of FIG. 4, the sides other than the folded side may be heat-sealed to form a package with a three-sided seal, or the material may be folded back 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. 4, a recess may be provided in one electrical storage device exterior packaging material and no recess may be provided in the other electrical storage device exterior packaging material, or a recess may be provided in the other electrical storage device exterior packaging material.

[0145] The exterior material for an electricity storage device according to the present disclosure can be suitably used in electricity storage devices such as batteries (including condensers, capacitors, etc.). The exterior material for an electricity storage device according to 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 material for an electricity storage device according to the present disclosure is 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 material for an electricity storage device according to the present disclosure. [Example]

[0146] The present disclosure will be described in detail below with reference to examples and comparative examples, but the present disclosure is not limited to the examples.

[0147] <Manufacturing of exterior materials for energy storage devices> Examples 1-4 and Comparative Examples 1-4 The exterior packaging materials for electricity storage devices of Examples 1-4 and Comparative Examples 1-4 were produced by the following procedure: Using the following two-component polyurethane adhesive AD (see Table 2), the base material layer and the barrier layer were laminated by dry lamination, and an aging treatment was carried out to produce a laminate of the base material layer / adhesive layer (thickness after curing: 3 μm) / barrier layer.

[0148] The two-component polyurethane adhesives AD used in the dry lamination method are as follows: Adhesive A: An adhesive that has resistance to moist heat after curing, which is a two-component polyurethane adhesive (glass transition temperature after curing: 134°C) that uses polyester polyol and an aromatic isocyanate compound. Adhesive B: A different adhesive from Adhesive A. It is a two-component polyurethane adhesive made from polyester polyol and an aromatic isocyanate compound, and has moist heat resistance after curing. Adhesive C: An adhesive used in solar cell backsheets that has high moist heat resistance after curing. It is a two-component polyurethane adhesive made from polyester polyol and an aliphatic isocyanate compound (glass transition temperature after curing: 163°C). Adhesive D: This adhesive is used in exterior materials for in-vehicle energy storage devices and has high heat resistance and formability after curing. It is a two-component polyurethane adhesive (glass transition temperature after curing: 152°C) made from polyester polyol and aromatic isocyanate compounds.

[0149] <Method for measuring glass transition temperature> The glass transition temperature of adhesive AD after curing was measured using a differential scanning calorimeter (DSC, TA Instruments Q200 differential scanning calorimeter). Specifically, using differential scanning calorimetry (DSC) according to the procedure of JIS K7121:2012 (Method for measuring transition temperatures of plastics (JIS K7121:1987, Supplement 1)), the cured adhesive layer was held at 30°C for 10 minutes, then heated from 30°C to 200°C at a heating rate of 10°C / min. The glass transition temperature was determined as the temperature at the intersection of a line extending the low-temperature baseline toward the high-temperature side and a tangent drawn at the point where the gradient of the step-like change in the glass transition curve was maximum. The adhesive layer measured was obtained by applying the adhesive (3 μm) to a polyethylene terephthalate (PET) film and subjecting it to aging treatment (using the same conditions (temperature and time) as the aging treatment in the examples).

[0150] The substrate layers were made of polyethylene terephthalate (PET) film (12 μm thick) and oriented nylon (ONy) film (15 μm thick). Three types of ONy films A, B, and C (ONyA, ONyB, and ONyC) with the physical properties (heat shrinkage and wet heat shrinkage) listed in Table 1 were used as the oriented nylon films (see Tables 1 and 2). The PET film and ONy film were bonded to each other by dry lamination using the two-component polyurethane adhesive (thickness after drying: 3 μm, see Table 2) described above to form the substrate layer.

[0151] Furthermore, as the barrier layer, aluminum alloy foil A (JIS H4160:1994 A8021H-O (thickness 40 μm)) was used in Examples 1, 3, and 4 and Comparative Examples 1-3, and aluminum alloy foil B (JIS H4160:1994 A8079H-O (thickness 40 μm)) was used in Example 2 and Comparative Example 4. Both sides of the aluminum alloy foil were subjected to chemical conversion treatment. The chemical conversion treatment of the aluminum alloy foil was carried out by using a treatment solution consisting of a phenolic resin, a chromium fluoride compound, and phosphoric acid, with a coating amount of chromium of 10 mg / m 2 (dry mass) by applying the coating solution to both sides of the aluminum alloy foil by roll coating, and baking the coating solution.

[0152] On the barrier layer of the substrate layer / adhesive layer (thickness after curing: 3 μm) / barrier layer laminate obtained above, maleic anhydride-modified polypropylene as an adhesive layer (thickness: 40 μm) and random polypropylene as a heat-sealable resin layer (thickness: 40 μm) were laminated on top of the barrier layer, thereby obtaining an exterior material for an electricity storage device in which the substrate layer (thickness: 30 μm including the adhesive layer between the PET film and the ONy film) / adhesive layer (3 μm) / barrier layer (40 μm) / adhesive layer (40 μm) / heat-sealable resin layer (40 μm) were laminated in that order.

[0153] Example 5 and Comparative Examples 5 and 6 ONy film D (produced in the same manner as ONy film C used in Comparative Example 4, except for the 25 μm thickness) was used as the substrate layer. Aluminum alloy foil B (JIS H4160:1994 A8079H-O (thickness 40 μm)) was prepared as the barrier layer. Using the two-component polyurethane adhesives A, C, and D (see Table 3), the substrate layer and barrier layer were laminated by dry lamination, and an aging treatment was performed to produce a substrate layer / adhesive layer (thickness after curing: 3 μm) / barrier layer laminate. Both sides of the aluminum alloy foil were subjected to chemical conversion treatment. The chemical conversion treatment of the aluminum alloy foil was performed using a treatment solution consisting of a phenolic resin, a chromium fluoride compound, and phosphoric acid, with a coating amount of chromium of 10 mg / m. 2 (dry mass) by applying the coating solution to both sides of the aluminum alloy foil by roll coating, and baking the coating solution.

[0154] Next, maleic anhydride-modified polypropylene as an adhesive layer (thickness 22.5 μm) and random polypropylene as a heat-sealable resin layer (thickness 22.5 μm) were laminated on the barrier layer of each of the laminates obtained above, thereby obtaining an exterior material for an electricity storage device in which the substrate layer (25 μm) / adhesive layer (3 μm) / barrier layer (40 μm) / adhesive layer (22.5 μm) / heat-sealable resin layer (22.5 μm) were laminated in this order.

[0155] <Measurement of heat shrinkage rate of stretched nylon film> The heat shrinkage (MD, TD, 45° and 135° directions) of ONy films A, B, C and D used in the examples and comparative examples was measured at a test temperature of 160°C for 30 minutes according to the method specified in JIS Z 1714: 2009. The average values ​​measured for three test samples are shown in Table 1 as the heat shrinkage.

[0156] <Measurement of wet heat shrinkage of stretched nylon film> For each of the ONy films A, B, C, and D used in the examples and comparative examples, the wet heat shrinkage (MD, TD, 45°, and 135° directions) was measured at a test temperature of 85°C, a relative humidity of 85%RH, and a heating time of 2 hours in accordance with the method specified in JIS Z 1714: 2009. The average values ​​measured for three test samples are shown in Table 1 as the wet heat shrinkage.

[0157] [Table 1]

[0158] <Heat resistance evaluation 1> In accordance with the provisions of JIS K7127:1999, the peel strength of the packaging materials for electricity storage devices was measured at each measurement temperature (room temperature (25°C) or 120°C) listed in Tables 2 and 3 as follows. A test sample was cut out from each packaging material for electricity storage devices into a strip shape with a width of 15 mm (TD direction) and a length of 150 mm (MD direction). The MD of the packaging material for electricity storage devices corresponds to the rolling direction (RD) of the aluminum alloy foil, and the TD of the packaging material for electricity storage devices corresponds to the TD of the aluminum alloy foil. Next, at one short side of the test sample, the side including the base layer and the side including the barrier layer were peeled at the interface between the adhesive layer and the barrier layer to an extent that they could be gripped with the grippers of a tensile tester (AG-Xplus (trade name) manufactured by Shimadzu Corporation), to prepare a test sample for measurement. Next, the test sample for measurement was attached to a tensile tester and left at each measurement temperature for 2 minutes. Subsequently, the peel strength (N / 15 mm) between the base layer and the barrier layer was measured using the tensile tester under the conditions of 180° peel, a pulling speed of 50 mm / min, and a gauge length of 50 mm. The strength when the gauge length reached 57 mm was taken as the peel strength (N / 15 mm), and the average value of three measurements of the peel strength (N / 15 mm) is shown in Tables 2 and 3. Tables 2 and 3 also show the ratio (%) of the peel strength at 120°C to the peel strength at room temperature. The evaluation criteria for heat resistance at room temperature and at 120°C were as follows: (Heat resistance evaluation standard at room temperature) A: Peel strength is 5.0N / 15mm or more C: Peel strength is less than 5.0N / 15mm (Heat resistance evaluation standard at 120°C) A: Peel strength is 3.0N / 15mm or more C: Peel strength is less than 3.0N / 15mm

[0159] <Moldability evaluation> For each of the above-mentioned electrical storage device packaging materials, test samples (with lubricant) in which erucic acid amide was applied as a lubricant to both sides of the electrical storage device packaging material (the surface of the base material layer and the surface of the heat-sealable resin layer), and test samples (without lubricant) in which no lubricant was applied were prepared, and cold forming was performed under the following conditions. First, each electrical storage device packaging material was cut into a rectangle with a length (MD direction) of 90 mm and a width (TD direction) of 150 mm to prepare a test sample. The MD of the electrical storage device packaging material corresponds to the rolling direction (RD) of the aluminum alloy foil, and the TD of the electrical storage device packaging material corresponds to the TD of the aluminum alloy foil. Next, each test sample was placed in a rectangular molding die (female die, the surface of which had a maximum height roughness (nominal value of Rz) of 3.2 μm, a corner curvature radius R of 2.0 mm, and a ridgeline curvature radius R of 1.0 mm, as specified in Table 2 of the surface roughness standard for comparison in JIS B 0659-1:2002, Annex 1 (Reference)) with a bore diameter of 31.6 mm (MD) x 54.5 mm (TD) in an environment of 25°C, and a corresponding molding die (male die, the surface of the ridgeline had a maximum height roughness (nominal value of Rz) of 1.6 μm, as specified in Table 2 of the surface roughness standard for comparison in JIS B 0659-1:2002, Annex 1 (Reference) Using the comparative surface roughness standard specimens specified in Table 2 (maximum height roughness (nominal Rz value) of 3.2 μm, corner curvature radius R of 2.0 mm, and ridge curvature radius R of 1.0 mm), cold forming (single-stage drawing) was performed on 10 test samples at each forming depth (5.0 mm to 8.5 mm) listed in Tables 2 and 3, with a pressing pressure (surface pressure) of 0.25 MPa. The test samples were placed on a female mold with the heat-sealable resin layer facing the male mold, and forming was performed at room temperature (25°C). The clearance between the male and female molds was 0.3 mm. After cold forming, the test samples were illuminated with a penlight in a dark room to check for pinholes or cracks in the aluminum alloy foil by light transmission. The number of test samples with pinholes or cracks was counted among 10 or more test samples.In Tables 2 and 3, for example, if pinholes or cracks occurred in two test samples out of a total of 10 test samples subjected to cold forming, this was expressed as 2 / 10. The criteria for formability evaluation are as follows: If the evaluation is A or B, it can be said that the packaging material for an electricity storage device has cold formability. A: The percentage of test samples with pinholes or cracks is 0 / 10. B: The percentage of test samples with pinholes or cracks is between 1 / 10 and 4 / 10. C: The percentage of test samples with pinholes or cracks is between 5 / 10 and 10 / 10.

[0160] Furthermore, for the cold-formed exterior packaging material for an electricity storage device, the deepest forming depth at which no pinholes or cracks occurred in the aluminum alloy foil in any of the 10 test samples was defined as A mm, and the number of test samples at which pinholes or the like occurred in the aluminum alloy foil at the shallowest forming depth was defined as B. The value calculated by the following formula was rounded to two decimal places to determine the limit forming depth of the exterior packaging material for an electricity storage device. The results are shown in Tables 2 and 3. Limit forming depth = A mm + (0.5 mm / 10 pieces) x (10 pieces - B pieces)

[0161] <Heat resistance evaluation 2> As in the above-described <Moldability Evaluation>, each electrical storage device packaging material was cut into a rectangular shape measuring 90 mm in length (MD) and 160 mm in width (TD). These test samples were then cold-formed using the above-described molding die. The molding depth was 5.0 mm in Examples 1-4 and Comparative Examples 2-4, and 7.0 mm in Example 5 and Comparative Example 6. No lubricant was applied to either side of each electrical storage device packaging material subjected to cold forming. Next, as shown in the schematic diagram of FIG. 6, the cold-formed test sample was folded at the position of dashed line P with the molding recess 21 of test sample 20 facing inward (so that the heat-sealable resin layers faced each other) (FIGS. 6(a) and 6(b)). Next, two heat-sealed locations were formed along the outer edge of the molding recess, first in the TD direction and then in the MD direction (FIG. 6(c)). In FIG. 6, the heat-sealed portion S1 in the TD direction and the heat-sealed portion S2 in the MD direction are indicated by hatched areas. The heat sealing conditions were the temperature (190°C or 210°C), surface pressure of 1.0 MPa, 3 seconds, and seal width of 7 mm, as shown in Tables 2 and 3. After heat sealing, the test samples were visually inspected for any lifting (peeling of the base layer) between the base layer and the barrier layer, and the percentage of test samples with lifting out of 10 test samples is shown in Tables 2 and 3. The criteria for heat resistance evaluation 2 are as follows: Evaluation A or Evaluation B indicates that the heat resistance of the cold-formed packaging material for an electricity storage device is high. A: The percentage of test samples in which floating occurred was 0 / 10. B: The percentage of test samples with floating was 1 / 10 to 4 / 10. C: The percentage of test samples with floating was between 5 / 10 and 10 / 10.

[0162] <Evaluation of moisture and heat resistance after molding> The wet heat resistance of the cold-formed packaging material for an electricity storage device was evaluated according to the following wet heat resistance evaluation 1-3.

[0163] (Heat and humidity resistance rating 1: temperature 65°C, relative humidity 90%RH) As in the above-described <Moldability Evaluation>, each electrical storage device packaging material was cut into a rectangular shape measuring 90 mm in length (MD) and 160 mm in width (TD). These test samples were then cold-formed using the above-described molding die. The molding depth was 5.0 mm in Examples 1-4 and Comparative Examples 2-4, and 7.0 mm in Example 5 and Comparative Example 6. No lubricant was applied to either side of each electrical storage device packaging material subjected to cold forming. Next, as shown in the schematic diagram of FIG. 6, the cold-formed test sample was folded at the position of dashed line P with the molding recess 21 of test sample 20 facing inward (so that the heat-sealable resin layers faced each other) (FIGS. 6(a) and 6(b)). Next, two heat-sealed locations were formed along the outer edge of the molding recess, first in the TD direction and then in the MD direction (FIG. 6(c)). In FIG. 6, the heat-sealed portion S1 in the TD direction and the heat-sealed portion S2 in the MD direction are indicated by hatched areas. The heat sealing conditions were a temperature of 190°C, a surface pressure of 1.0 MPa, 3 seconds, and a seal width of 7 mm. Next, the heat-sealed test samples were placed in a thermo-hygrostat chamber at a temperature of 65°C and a relative humidity of 90% RH, and left to stand for 72 hours (3 days). The test samples were removed from the thermo-hygrostat chamber and visually inspected for any lifting (peel-off of the substrate layer) between the base layer and the barrier layer. The percentage of test samples with lifting out of 10 test samples is shown in Tables 2 and 3. The criteria for moist heat resistance evaluation 1 are as follows: A rating of A or B indicates that the moist heat resistance of the cold-formed electrical energy storage device packaging material is high. A: The percentage of test samples in which floating occurred was 0 / 10. B: The percentage of test samples with floating was 1 / 10 to 4 / 10. C: The percentage of test samples with floating was between 5 / 10 and 10 / 10.

[0164] (Heat and humidity resistance rating 2: temperature 85°C, relative humidity 85%RH) Evaluation 2 of moist heat resistance was carried out in the same manner as Evaluation 1 of moist heat resistance, except that instead of "putting the sample in a thermo-hygrostat chamber at a temperature of 65°C and a relative humidity of 90% RH and leaving it there for 72 hours," the sample was "put in a thermo-hygrostat chamber at a temperature of 85°C and a relative humidity of 85% RH and left there for 10, 20, or 30 days." The results are shown in Tables 2 and 3. The evaluation criteria for Evaluation 2 of moist heat resistance were as follows: A: The percentage of test samples in which floating occurred was 0 / 10. B: The percentage of test samples with floating was 1 / 10 to 4 / 10. C: The percentage of test samples with floating was between 5 / 10 and 10 / 10.

[0165] (Heat and humidity resistance rating 3: 120°C, saturated steam environment) The electrical storage device packaging material was prepared into a test sample that was rectangular in plan view, measuring 120 mm in the TD direction and 80 mm in the MD direction. The number of test samples was 12. As described above, the MD of the electrical storage device packaging material corresponded to the rolling direction (RD) of the aluminum alloy foil, and the TD of the electrical storage device packaging material corresponded to the TD of the aluminum alloy foil. Next, as cold-forming molds, a male mold that was rectangular in plan view, measuring 54.5 mm in the TD direction and 31.6 mm in the MD direction, and a female mold with a clearance of 0.5 mm from the male mold were prepared. The surface of the ridge of the male mold has a maximum height roughness (nominal Rz value) of 1.6 μm as specified in Table 2 of the surface roughness standard for comparison in JIS B 0659-1:2002, Appendix 1 (Reference), and the surface other than the ridge has a maximum height roughness (nominal Rz value) of 3.2 μm, a corner curvature radius R of 2.0 mm, and a ridge curvature radius R of 1.0 mm as specified in Table 2 of the surface roughness standard for comparison in JIS B 0659-1:2002, Appendix 1 (Reference).The surface of the female mold has a maximum height roughness (nominal Rz value) of 3.2 μm, a corner curvature radius R of 2.0 mm, and a ridge curvature radius R of 1.0 mm as specified in Table 2 of the surface roughness standard for comparison in JIS B 0659-1:2002, Appendix 1 (Reference). The test sample was placed on the female mold with the heat-sealable resin layer facing the male mold. Next, the test sample was pressed with a surface pressure of 0.13 MPa and subjected to cold forming in a single stage. The forming depth was 5.0 mm in Examples 1-4 and Comparative Examples 2-4, and 6.5 mm in Example 5 and Comparative Example 6. Next, the cold-formed test sample was placed in an autoclave. The autoclave was kept at 120°C and saturated with steam, and the test sample was left standing for the specified time (8 hours, 10 hours, or 12 hours) listed in Tables 2 and 3. Next, the test sample was removed from the autoclave, and the interface between the substrate layer and the barrier layer was visually inspected to determine whether delamination had occurred between these layers. The percentage of test samples with lifting among the 12 test samples is shown in Tables 2 and 3. The evaluation criteria for moist heat resistance evaluation 3 are as follows: A: The percentage of test samples in which floating occurred was 0 / 12. B: The percentage of test samples with floating was between 1 / 12 and 4 / 12. C: The percentage of test samples with floating was between 5 / 12 and 12 / 12.

[0166] [Table 2]

[0167] [Table 3]

[0168] In Tables 2 and 3, the symbol "-" indicates that no measurement was performed. In Comparative Examples 1 and 5, the adhesive used to form the adhesive layer was the same as that used in solar cell backsheets, and while it had excellent moist heat resistance, it did not have cold formability (i.e., when subjected to cold forming at the aforementioned forming depth of 5.0 mm, pinholes and cracks occurred in all test samples). Therefore, evaluation of formability was not performed, and evaluation of heat resistance was omitted. Note that in Comparative Examples 1 and 5, moist heat resistance evaluations 1-3 were performed without cold forming the test samples.

[0169] As shown in Tables 2 and 3, the electrical storage device packaging materials of Examples 1-5 have high moist heat resistance when cold-formed (for example, have moist heat resistance at a temperature of 120°C and in a saturated steam environment), which also shows that the adhesive layer bonding the base material layer and barrier layer has high moist heat resistance. In the electrical storage device packaging materials of Examples 1-5, the adhesive layer bonding the base material layer and barrier layer has moist heat resistance, and the electrical storage device packaging materials can be cold-formed.

[0170] In contrast, the packaging materials of Comparative Examples 1 and 5, which used a solar cell adhesive with excellent moist heat resistance, cannot be cold-formed, and therefore cannot be used as packaging materials for electricity storage devices that are subjected to cold forming.Furthermore, the packaging materials of Comparative Examples 2-4 and 6 used an adhesive that is used in packaging materials for in-vehicle electricity storage devices, which has high heat resistance and formability after curing, and therefore it was revealed that although they had excellent heat resistance, their moist heat resistance was insufficient.

[0171] As described above, the present disclosure provides the following aspects of the invention. Item 1. The laminate is composed of at least a base layer, an adhesive layer, a barrier layer, and a heat-sealable resin layer in this order, The adhesive layer has moisture and heat resistance, The laminate is a packaging material for an electricity storage device that can be cold-formed. Item 2. The packaging material for an electricity storage device according to Item 1, wherein the adhesive layer has moist heat resistance at a temperature of 120°C and in a saturated water vapor environment. Item 3. The packaging material for an electricity storage device according to Item 1 or 2, wherein, when peeling between the base material layer and the barrier layer of the packaging material for an electricity storage device after cold forming is confirmed using the moist heat resistance evaluation method described below, peeling occurs in 4 or less test samples out of a total of 12 test samples of the packaging material for an electricity storage device. (Method for evaluating humidity and heat resistance) The test samples were each an exterior material for an electricity storage device. The number of test samples was 12. Next, a cold-forming mold was prepared: a male mold having a rectangular shape in plan view, measuring 54.5 mm in the TD direction and 31.6 mm in the MD direction, and a female mold with a clearance of 0.5 mm from the male mold. The test sample was placed on the female mold with the heat-sealable resin layer side of the test sample positioned on the male mold side. Next, the test sample was pressed with a surface pressure of 0.13 MPa and subjected to cold forming in a single pull-in stage. Next, the test sample after cold forming was placed in an autoclave. The autoclave was set to a temperature of 120°C and saturated steam environment, and the test sample was left standing for 10 hours. Next, the test sample was removed from the autoclave, and the substrate layer and the barrier layer were visually observed to confirm whether delamination had occurred between these layers. Item 4. The packaging material for an electricity storage device according to any one of Items 1 to 3, wherein the adhesive layer has a glass transition temperature of 40°C or higher and 150°C or lower. Item 5. The packaging material for an electricity storage device according to any one of Items 1 to 3, wherein the adhesive layer has a glass transition temperature of 111°C or higher and 139°C or lower. Item 6. The packaging material for an electricity storage device according to any one of Items 1 to 5, which is used as a packaging material for an electricity storage device to be installed outdoors. Item 7. 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 packaging material for an electricity storage device according to any one of Items 1 to 6. Item 8. The method includes a step of laminating at least a base layer, an adhesive layer, a barrier layer, and a heat-sealable resin layer in this order to obtain a laminate, The adhesive layer has moisture and heat resistance, The method for producing an exterior material for an electricity storage device, wherein the laminate is cold-formable. [Explanation of symbols]

[0172] 1 Base material layer 2 Adhesive layer 3 Barrier layer 4 Heat-fusible resin layer 5 Adhesive layer 6 Surface coating layer 10. Exterior materials for energy storage devices

Claims

1. It is composed of a laminate comprising, at least, a base layer, an adhesive layer, a barrier layer, and a heat-fusible resin layer in this order. In accordance with the provisions of JIS Z 1714:2009, the resin film contained in the substrate layer is used as a test sample, and the moist heat shrinkage rate (MD direction, TD direction, 45° direction, 135° direction) is measured under the conditions of a test temperature of 85°C, relative humidity of 85%RH, and heating time of 2 hours. When the average value measured for three test samples is taken as the moist heat shrinkage rate, the moist heat shrinkage rate is 3.0% or less. The adhesive layer has moisture and heat resistance, The laminate is cold-formable, The adhesive layer having the moisture and heat resistance means that, using the moisture and heat resistance evaluation method described below, when peeling between the base material layer and the barrier layer is confirmed for the exterior material for the energy storage device after cold forming, four or fewer test samples out of a total of twelve test samples of the exterior material for the energy storage device exhibit peeling. (Method for evaluating resistance to moisture and heat) Exterior material for energy storage devices will be used as the test sample. The number of test samples will be 12. Next, a male mold with a rectangular shape in plan view, with a TD direction of 54.5 mm and an MD direction of 31.6 mm, and a female mold with a clearance of 0.5 mm from the male mold will be prepared as a mold for cold forming. The test sample is placed on the female mold so that the heat-fusible resin layer side of the test sample is positioned on the male mold side. Next, the test sample is pressed with a surface pressure of 0.13 MPa and subjected to cold forming in one stage of pull-in. Next, the cold-formed test sample is placed in an autoclave. The environment inside the autoclave is set to a temperature of 120°C and a saturated water vapor environment, and left to stand for 10 hours. Next, the test sample is removed from the autoclave, and the space between the substrate layer and the barrier layer is visually observed to confirm whether or not delamination has occurred between these layers.

2. The exterior material for an energy storage device according to Claim 1, wherein the glass transition temperature of the adhesive layer is 111°C or higher and 139°C or lower.

3. The exterior material for an energy storage device according to claim 1 or 2, for use as an exterior material for an energy storage device installed outdoors.

4. The exterior material for an energy storage device according to any one of claims 1 to 3, wherein the base layer comprises a polyester film and a polyamide film.

5. The exterior material for an energy storage device according to any one of claims 1 to 4, wherein at least one of the surface and interior of the base material layer contains two or more types of lubricants.

6. The thickness of the substrate layer is 50 μm or less, The thickness of the substrate layer is 35 μm or less. Alternatively, the exterior material for an energy storage device according to any one of claims 1 to 5, wherein the thickness of the base material layer is greater than 35 μm and less than or equal to 50 μm.

7. The thickness of the barrier layer is 200 μm or less, The thickness of the barrier layer is 50 μm or less. Alternatively, the exterior material for an energy storage device according to any one of claims 1 to 6, wherein the thickness of the barrier layer is greater than 50 μm and less than or equal to 200 μm.

8. A lubricant is present on the surface of the heat-fusible resin layer, The exterior material for an energy storage device according to any one of claims 1 to 7, wherein the amount of the lubricant present is 10 mg / m² or more.

9. The exterior material for an energy storage device according to any one of claims 1 to 8, wherein the heat-sealable resin layer is composed of a resin containing a polyolefin skeleton.

10. The heat-sealable resin layer comprises at least one selected from the group consisting of polyolefin, cyclic polyolefin, acid-modified polyolefin, and acid-modified cyclic polyolefin, as an exterior material for an energy storage device according to any one of claims 1 to 9.

11. The exterior material for an energy storage device according to any one of claims 1 to 10, wherein the heat-sealable resin layer is formed from a blended polymer of two or more resins.

12. The exterior material for an energy storage device according to any one of claims 1 to 11, wherein the heat-fusible resin layer is formed of two or more layers of the same or different resins.

13. The exterior material for an energy storage device according to any one of claims 1 to 12, wherein at least one of the surface and interior of the heat-fusible resin layer contains two or more types of lubricants.

14. The exterior material for an energy storage device according to any one of claims 1 to 13, wherein at least two types selected from the group consisting of 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 are present on the surface and inside of the heat-fusible resin layer.

15. The exterior material for an energy storage device according to any one of claims 1 to 14, wherein the barrier layer comprises at least one of an aluminum alloy foil and a stainless steel foil.

16. An energy storage device in which an energy storage device element comprising at least a positive electrode, a negative electrode, and an electrolyte is housed in a package formed from an outer material for an energy storage device according to any one of claims 1 to 15.

17. A method for manufacturing an exterior material for an energy storage device, comprising the step of obtaining a laminate by laminating a base material layer, an adhesive layer, a barrier layer, and a heat-fusible resin layer in this order, In accordance with the provisions of JIS Z 1714:2009, the resin film contained in the substrate layer is used as a test sample, and the moist heat shrinkage rate (MD direction, TD direction, 45° direction, 135° direction) is measured under the conditions of a test temperature of 85°C, relative humidity of 85%RH, and heating time of 2 hours. When the average value measured for three test samples is taken as the moist heat shrinkage rate, the moist heat shrinkage rate is 3.0% or less. The adhesive layer has moisture and heat resistance, The laminate is cold-formable, The adhesive layer having the moisture and heat resistance means that, using the moisture and heat resistance evaluation method described below, when peeling between the base material layer and the barrier layer is confirmed for the exterior material for the energy storage device after cold forming, four or fewer test samples out of a total of twelve test samples of the exterior material for the energy storage device exhibit peeling. (Method for evaluating resistance to moisture and heat) Exterior material for energy storage devices will be used as the test sample. The number of test samples will be 12. Next, a male mold with a rectangular shape in plan view, with a TD direction of 54.5 mm and an MD direction of 31.6 mm, and a female mold with a clearance of 0.5 mm from the male mold will be prepared as a mold for cold forming. The test sample is placed on the female mold so that the heat-fusible resin layer side of the test sample is positioned on the male mold side. Next, the test sample is pressed with a surface pressure of 0.13 MPa and subjected to cold forming in one stage of pull-in. Next, the cold-formed test sample is placed in an autoclave. The environment inside the autoclave is set to a temperature of 120°C and a saturated water vapor environment, and left to stand for 10 hours. Next, the test sample is removed from the autoclave, and the space between the substrate layer and the barrier layer is visually observed to confirm whether or not delamination has occurred between these layers.

18. The barrier layer and the heat-fusible resin layer are provided with an adhesive layer, The method for manufacturing an exterior material for an energy storage device according to claim 17, wherein the adhesive layer and the heat-fusible resin layer are formed by co-extrusion lamination, tandem lamination, thermal lamination, sandwich lamination, or by a method of solution coating an adhesive for forming the adhesive layer onto a barrier layer and laminating the heat-fusible resin layer, which has been previously formed into a sheet, onto the adhesive layer.

19. The barrier layer and the heat-fusible resin layer are provided with an adhesive layer, The method for manufacturing an exterior material for an energy storage device according to claim 17 or 18, wherein the heat-fusible resin layer is formed of two or more layers of the same or different resins.

Images