Exterior material for a storage device, method of manufacturing the same, and storage device

Abstract

An outer casing for a storage device, comprising a laminate having at least a substrate layer, a barrier layer, and a heat-fusible resin layer in this order, wherein the substrate layer comprises a polyester film, and the polyester film has a work hardening index in both the length direction and the width direction of 1.6 or more and 3.0 or less, and the difference between the work hardening index in the length direction and the width direction is 0.5 or less, the intrinsic viscosity is 0.66 or more and 0.95 or less, and the rigidity specific amount is 28% or more and 60% or less.

Description

Technology Field

[0001] The present disclosure relates to an outer casing for a storage device, a method for manufacturing the same, and a storage device. Background Technology

[0002] Conventionally, although various types of capacitor devices have been developed, packaging materials (outer casings) have become an indispensable component for encapsulating capacitor device elements such as electrodes and electrolytes in all capacitor devices. Conventionally, metal outer casings have been widely used as outer casings for capacitor devices.

[0003] Meanwhile, with the recent increase in performance of electric vehicles, hybrid electric vehicles, PCs, cameras, and mobile phones, there is a growing demand for energy storage devices to have diverse shapes, as well as to be thinner and lighter. However, conventional metal casings widely used for energy storage devices have drawbacks, such as difficulty in keeping up with the diversification of shapes and limitations in weight reduction.

[0004] Accordingly, conventionally, a film-type exterior material has been proposed in which a substrate, an aluminum foil layer, and a heat-fusible resin layer are sequentially laminated, as an exterior material for a capacitor device that is easy to process into various shapes and can achieve thinning or weight reduction (for example, see Patent Document 1).

[0005] In such a film-type exterior material, a concave portion is generally formed by cold forming, a capacitor device element such as an electrode or an electrolyte is placed in the space formed by the concave portion, and by heat-fusion of the heat-fusible resin layers, a capacitor device having a capacitor device element housed inside the exterior material is obtained. Prior art literature

[0006] Japanese Patent Publication No. 2008-287971 The problem to be solved

[0007] In film-type casings, it is required to form deep recesses within the casing to accommodate capacitor elements, from the perspective of further improving the energy density of capacitor devices. However, when forming recesses by molding the film-type casing, there is a problem in that cracks or pinholes are prone to occur.

[0008] Here, as the substrate layer of the film-type exterior material, for example, a polyamide film or a polyester film is used, and in order to improve the moldability of the exterior material, it is preferable to use a polyamide film.

[0009] However, while polyamide films have excellent moldability compared to polyester films, their mechanical strength and insulation properties are inferior; therefore, a technology is required to improve the moldability of exterior materials for capacitor devices by using a polyester film in the substrate layer.

[0010] The present disclosure aims to provide an exterior material for a storage device with excellent moldability, comprising a laminate having, at least, a substrate layer including a polyester film, a barrier layer, and a heat-fusible resin layer in this order. means of solving the problem

[0011] The inventors of the present disclosure have conducted a thorough investigation to solve the above problem. As a result, they discovered that in an outer casing for a capacitor device comprising a laminate having, at least, a substrate layer including a polyester film, a barrier layer, and a heat-fusible resin layer in this order, the work hardening index of the polyester film in the length direction and width direction, the difference between the work hardening index in the length direction and width direction, the intrinsic viscosity, and furthermore, the rigidity non-crystalline quantity, the outer casing for the capacitor device exhibits excellent moldability by setting these values ​​within a specific range.

[0012] The present disclosure is completed by further examining the findings above. That is, the present disclosure provides the invention of the following aspects.

[0013] At least, it is composed of a laminate having a substrate layer, a barrier layer, and a heat-fusible resin layer in this order, and

[0014] The above substrate layer comprises a polyester film, and

[0015] The above polyester film is an outer material for a capacitor device, wherein the work hardening index in both the length direction and the width direction is 1.6 or higher and 3.0 or lower, the difference between the work hardening index in the length direction and the width direction is 0.5 or lower, the intrinsic viscosity is 0.66 or higher and 0.95 or lower, and the rigidity specific amount is 28% or higher and 60% or lower. Effects of the invention

[0016] According to the present disclosure, an exterior material for a storage device is provided, comprising a laminate having, at least, a substrate layer including a polyester film, a barrier layer, and a heat-fusible resin layer in this order, and having excellent moldability. Additionally, according to the present disclosure, a method for manufacturing an exterior material for a storage device and a storage device may be provided. Brief explanation of the drawing

[0017] FIG. 1 is a schematic diagram showing an example of a cross-sectional structure of an outer casing for a capacitor device according to the present disclosure. FIG. 2 is a schematic diagram showing an example of a cross-sectional structure of an outer casing for a capacitor device according to the present disclosure. FIG. 3 is a schematic diagram showing an example of a cross-sectional structure of an outer casing for a capacitor device according to the present disclosure. FIG. 4 is a schematic diagram showing an example of a cross-sectional structure of an outer casing for a capacitor device according to the present disclosure. FIG. 5 is a schematic diagram illustrating a method for accommodating a capacitor device element in a packaging formed by an outer casing for a capacitor device according to the present disclosure. Specific details for implementing the invention

[0018] The outer casing for a capacitor device of the present disclosure is composed of a laminate having at least a substrate layer, a barrier layer, and a heat-fusible resin layer in that order, wherein the substrate layer comprises a polyester film, and the polyester film is characterized in that the work hardening index in the longitudinal and width directions is 1.6 or higher and 3.0 or lower, the difference between the work hardening index in the longitudinal and width directions is 0.5 or lower, the intrinsic viscosity is 0.66 or higher and 0.95 or lower, and the rigidity specific amount is 28% or higher and 60% or lower. By having such a configuration, the outer casing for a capacitor device of the present disclosure has excellent moldability despite the use of a substrate layer comprising a polyester film.

[0019] Hereinafter, the outer casing for a capacitor device of the present disclosure is described in detail. In addition, in this specification, numerical ranges indicated by “∼” mean “greater than or equal to” or “less than or equal to”. For example, the notation 2 to 15 mm means 2 mm or more and 15 mm or less.

[0020] In addition, regarding the outer casing for a capacitor device, the Machine Direction (MD) and Transverse Direction (TD) during the manufacturing process can typically be determined for the barrier layer described below. For example, when the barrier layer is composed of a metal foil such as an aluminum alloy foil or a stainless steel foil, a linear line known as a so-called rolling mark is formed on the surface of the metal foil in the rolling direction (RD) of the metal foil. Since the rolling mark extends along the rolling direction, the rolling direction of the metal foil can be determined by observing the surface of the metal foil. Furthermore, during the manufacturing process of a laminate, the MD of the laminate and the RD of the metal foil usually coincide; therefore, the MD of the laminate can be determined by observing the surface of the metal foil of the laminate and determining the rolling direction (RD) of the metal foil. Additionally, since the TD of the laminate is perpendicular to the MD of the laminate, the TD of the laminate can also be determined.

[0021] In addition, if the MD of the casing material for a capacitor device cannot be determined by rolling marks on metal foils such as aluminum alloy foil or stainless steel foil, it can be determined by the following method. As a method for confirming the MD of the casing material for a capacitor device, there is a method of confirming the island structure by observing the cross-section of the heat-fusible resin layer of the casing material for a capacitor device using an electron microscope. In the above method, the direction parallel to the cross-section where the average diameter of the island shape in the direction perpendicular to the thickness direction of the heat-fusible resin layer is maximum can be determined as the MD. Specifically, the island structure is confirmed by observing each cross-section (a total of 10 cross-sections)—which changes the angle by 10 degrees from the direction parallel to the lengthwise cross-section and extends to the direction perpendicular to the lengthwise cross-section—using electron microscope images. Next, the shape of each individual island is observed in each cross-section. For each island shape, the straight-line distance connecting the leftmost end in the direction perpendicular to the thickness direction of the heat-fusible resin layer and the rightmost end in the direction perpendicular is defined as the diameter y. For each cross-section, the average of the top 20 diameters y of the island shapes is calculated in order of largest diameter y. The direction parallel to the cross-section with the largest average diameter y of the island shapes is determined as MD.

[0022] 1. Laminated structure of exterior materials for energy storage devices

[0023] The outer casing (10) for a capacitor device of the present disclosure is composed of a laminate having a substrate layer (1), a barrier layer (3), and a heat-fusible resin layer (4) in this order, for example, as shown in FIG. 1. In the outer casing (10) for a capacitor device, the substrate layer (1) is the outermost layer, and the heat-fusible resin layer (4) is the innermost layer. When assembling a capacitor device using the outer casing (10) for a capacitor device and a capacitor device element, the capacitor device element is accommodated in a space formed by heat-fusing the surrounding edge portions while the heat-fusible resin layers (4) of the outer casing (10) for a capacitor device are facing each other. In the laminated body constituting the outer casing (10) for the capacitor device of the present disclosure, with respect to the barrier layer (3), the heat-fusible resin layer (4) side is on the inner side than the barrier layer (3), and the substrate layer (1) side is on the outer side than the barrier layer (3).

[0024] The outer casing (10) for the capacitor device may have an adhesive layer (2) between the base layer (1) and the barrier layer (3) as needed, for the purpose of increasing the adhesion between these layers, as shown in FIGS. 2 to 4, for example. Additionally, as shown in FIGS. 3 and 4, it may have an adhesive layer (5) between the barrier layer (3) and the heat-fusible resin layer (4) as needed, for the purpose of increasing the adhesion between these layers. Furthermore, as shown in FIG. 4, a surface coating layer (6), etc., may be installed on the outer side of the base layer (1) (opposite side to the heat-fusible resin layer (4)) as needed.

[0025] The thickness of the laminate constituting the outer casing (10) for the energy storage device is not particularly limited, but from the perspective of cost reduction and energy density improvement, it is preferably about 190 μm or less, about 155 μm or less, or about 120 μm or less. In addition, regarding the thickness of the laminate constituting the outer casing (10) for the energy storage device, from the perspective of maintaining the function of the outer casing for the energy storage device, which is to protect the energy storage device element, it is preferably about 35 μm or more, about 45 μm or more, or about 60 μm or more. In addition, regarding the preferred range of the laminate constituting the outer material (10) for the storage device, for example, about 35 to 190 μm, about 35 to 155 μm, about 35 to 120 μm, about 45 to 190 μm, about 45 to 155 μm, about 45 to 120 μm, about 60 to 190 μm, about 60 to 155 μm, about 60 to 120 μm, and particularly about 60 to 155 μm is preferred.

[0026] In an exterior material (10) for a storage device, the ratio of the total thickness of the substrate layer (1), the adhesive layer (2) installed as needed, the barrier layer (3), the adhesive layer (5) installed as needed, the heat-fusible resin layer (4), and the surface coating layer (6) installed as needed to the thickness (total thickness) of the laminate constituting the exterior material (10) for the 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 exterior material (10) for a storage device of the present disclosure includes a substrate layer (1), an adhesive layer (2), a barrier layer (3), an adhesive layer (5), and a heat-fusible resin layer (4), the ratio of the total thickness of each of these layers to the thickness (total thickness) of the laminate constituting the exterior material (10) for the storage device is preferably 90% or more, more preferably 95% or more, and even more preferably 98% or more. In addition, even when the outer casing (10) for a capacitor device of the present disclosure is a laminate comprising a substrate layer (1), an adhesive layer (2), a barrier layer (3), and a heat-fusible resin layer (4), the ratio of the total thickness of each of these layers to the thickness (total thickness) of the laminate constituting the outer casing (10) for a capacitor device can be, for example, 80% or more, preferably 90% or more, more preferably 95% or more, and even more preferably 98% or more.

[0027] 2. Each layer forming the outer casing for the capacitor device

[0028] [Recording layer (1)]

[0029] In the present disclosure, the substrate layer (1) is a layer installed for the purpose of performing the function of an outer layer for a storage device. The substrate layer (1) is located on the outer layer side of the outer layer for a storage device. The substrate layer (1) may be the outermost layer (a layer constituting the outer surface), and for example, if a surface coating layer (6) described later is installed, the surface coating layer (6) may be the outermost layer (a layer constituting the outer surface).

[0030] In the present disclosure, the substrate layer (1) comprises a polyester film, and the polyester film is characterized in that the work hardening index in the length direction and the width direction is both 1.6 or higher and 3.0 or lower, the difference between the work hardening index in the length direction and the width direction is 0.5 or lower, the intrinsic viscosity is 0.66 or higher and 0.95 or lower, and the rigidity specific amount is 28% or higher and 60% or lower.

[0031] Below, the polyester film included in the substrate layer (1) is described in detail.

[0032] In the present disclosure, the polyester film included in the substrate layer (1) has a work hardening index in both the length direction and the width direction of 1.6 or higher and 3.0 or lower. Here, the work hardening index is a value calculated from the stress at 5% elongation and the stress at 60% elongation, which is obtained from a tensile test determined by the method described in the evaluation method of the example described below, “(10) Work Hardening Index.”

[0033] A laminate used as an exterior material for a capacitor device includes a substrate layer, a barrier layer, and a heat-fusible resin layer, and among these, the substrate layer tends to be designed to be the thinnest. When drawing molding is performed on an exterior material for a capacitor device, the stress applied in the thickness direction determines the neutral axis according to the work hardening state of each layer, and determines where the stress is concentrated in the thickness direction. If the work hardening state of the polyester film, that is, the work hardening index, is less than 1.6, the neutral axis is skewed toward the barrier layer and the heat-fusible resin layer, and stress is likely to be applied unevenly to the barrier layer, and as a result, fracture or pinholes in the barrier layer occur during the drawing process. For this reason, in the substrate layer (1) of the present disclosure, the polyester film needs to have a work hardening index of at least 1.6. In order to prevent the neutral axis from shifting toward the outermost layer, the work hardening index needs to be 3.0 or less in either the length direction or the width direction.

[0034] In order to make the work hardening index of the polyester film in both the length direction and the width direction 1.6 or higher and 3.0 or lower, for example, it is desirable to make the breaking strength in the length direction and the width direction of the film 200 MPa or higher. And, here, the length direction and the width direction of the film are determined by measuring the breaking strength in any direction (0°) of the film and in directions 15°, 30°, 45°, 60°, 75°, 90°, 105°, 120°, 135°, 150°, and 165° from the said direction, and the direction with the highest breaking strength is designated as the width direction, and the direction perpendicular to the width direction is designated as the length direction.

[0035] To achieve a breaking strength of 200 MPa or higher for a polyester film, it is desirable to stretch the film at a high magnification during manufacturing. Specifically, biaxial stretching is most preferable, and it is sufficient to stretch the film sequentially or simultaneously at an area stretching magnification of 11.0 times or higher using known methods. If the work hardening index is less than 1.6, the drawing formability is poor. Furthermore, as the work hardening index increases, the elastic deformation caused by bending during drawing forming increases, so there is a tendency for warping after forming to increase. For this reason, it is important to keep the work hardening index to a minimum depending on the required degree of warping.

[0036] In order to more preferably exhibit the effects of the present invention, the work hardening index of the polyester film is preferably 1.8 or higher, and more preferably 2.0 or higher. In addition, the work hardening index of the polyester film is preferably 2.9 or lower. Examples of preferred ranges for the work hardening index of the polyester film include approximately 1.6 to 3.0, approximately 1.6 to 2.9, approximately 1.8 to 3.0, approximately 1.8 to 2.9, approximately 2.0 to 3.0, and approximately 2.0 to 2.9.

[0037] In the present disclosure, with respect to in-plane uniformity, the difference in work hardening index between the length direction and the width direction of the polyester film is 0.5 or less. If the difference in work hardening index between the length direction and the width direction exceeds 0.5, the in-plane uniformity is low, uneven loading is applied during drawing processing, local deformation occurs, and drawing formability is poor. The difference in work hardening index is preferably 0.3 or less.

[0038] In the present disclosure, it is preferable that the elongation at break in at least one of the longitudinal and transverse directions of the polyester film be 100% or more. One of the deformation behaviors of a material during drawing processing is elongation. The greater the elongation of the film, the larger the element that can be stretched and deformed during deformation behavior, and the drawing processability improves. For this reason, it is preferable that the elongation at break in at least one of the longitudinal and transverse directions be 100% or more, and it is more preferable that the elongation at break in both the longitudinal and transverse directions be 100% or more. To make the elongation at break in the longitudinal and transverse directions 100% or more, it can be adjusted by ensuring that the elongation ratio in either direction is 4.0 times or less. If there is a direction in which the elongation ratio exceeds 4.0 times, it is advantageous in terms of increasing the work hardening index, but the elongation at break in the above elongation direction becomes 100% or less, and the drawing formability may be reduced. The range of elongation at break in both the length and width directions of the polyester film is preferably about 110 to 150%. The elongation at break of the polyester film is measured by the method described in “(6) Elongation at Break” of the evaluation method of the example described below.

[0039] In the present disclosure, the polyester film has a rigidity specific amount of 28% or more and 60% or less relative to the entire film. Here, the rigidity specific amount is a value measured by the method described in the evaluation method “(8) rigidity specific amount” of the example described below. By having the rigidity specific amount within this range, puncture resistance, which is a particularly significant characteristic in the thickness direction, can be obtained. The drawing process performed on the outer material for a capacitor device is generally a process in which four corners are fixed with a die and drawing is performed in the thickness direction. By controlling the rigidity specific amount of the entire film to this range, excellent drawing processing characteristics are exhibited in the aforementioned drawing process. If the rigidity specific amount exceeds 60%, the amorphous component occupies most of the bulk composition of the film, and the dimensional stability of the film is significantly reduced. On the other hand, if the rigidity specific amount is less than 28%, puncture resistance, which is a characteristic in the thickness direction, is inferior.

[0040] In order to more preferably exhibit the effects of the present invention, the specific rigidity of the polyester film is preferably 30% or more, more preferably 35% or more. In addition, the specific rigidity of the polyester film is preferably 58% or less, more preferably 55% or less, and more preferably 53% or less. Examples of preferred ranges for the specific rigidity of the polyester film include approximately 28-60%, approximately 28-58%, approximately 28-55%, approximately 28-53%, approximately 30-60%, approximately 30-58%, approximately 30-55%, approximately 30-53%, approximately 35-60%, approximately 35-58%, approximately 35-55%, and approximately 35-53%.

[0041] Regarding the bulk state of the film, it is determined by the crystallinity of the raw material used and the film-making conditions. For example, when polyethylene terephthalate is used, in order to make the rigidity specific quantity 28% or more, there are means to make the film plane orientation coefficient fn 0.165 or more. Here, the film plane orientation coefficient is measured by the method described in the evaluation method of the example described later, “(5) Planar orientation coefficient fn of polyester film.” To make the film plane orientation coefficient 0.165 or more, examples of methods include making the area stretching ratio during biaxial stretching 12.25 times or more. In addition, it is desirable to control the rigidity specific quantity by the heat treatment temperature after sequential biaxial stretching, and it is important to keep the highest temperature applied during film making (heat treatment temperature) 200°C or less. On the other hand, when the heat treatment temperature is set to 230°C or higher, the melting of the resin begins, and the rigidity ratio tends to increase. However, since the crystallization of the film by heat is promoted, the degree of crystallization described later increases, and the degree of crystallization becomes higher than the rigidity ratio as a bulk composition of the film. For this reason, it is important to keep the heat treatment temperature at 200°C or lower. When the heat treatment temperature of the film exceeds 200°C and is less than 230°C, the rigidity ratio may be less than 28%.

[0042] In order to more preferably exhibit the effects of the present invention, it is preferable that the polyester film has a degree of crystallization of 15% or more and 40% or less. It is possible to control the degree of crystallization by oriented crystallization by stretching or by crystallization by heat, and to increase the mechanical strength of the film. If the degree of crystallization is less than 15%, the film plane orientation is insufficient, and the work hardening index may not be controlled within the range of the present disclosure; and if the degree of crystallization exceeds 40%, the rigidity ratio may not be controlled within the range of the present disclosure. To make the degree of crystallization 15% or more and 40% or less, for example, it can be adjusted by using a homopolyester resin to set the film plane orientation coefficient to 0.165 or more and 0.170 or less, and then setting the heat treatment temperature to 150°C or more and 200°C or less, but it is acceptable to mix other resins. The degree of crystallinity of the polyester film is measured by the method described in “(7) degree of crystallinity” of the evaluation method of the example described below.

[0043] In order to more preferably exhibit the effects of the present invention, the degree of crystallization of the polyester film is preferably 16% or more, more preferably 18% or more, and even more preferably 20% or more. In addition, the degree of crystallization of the polyester film is preferably 39% or less, more preferably 35% or less, and even more preferably 32% or less. Preferable ranges for the degree of crystallinity of the polyester film include about 15-40%, about 15-39%, about 15-35%, about 15-32%, about 16-40%, about 16-39%, about 16-35%, about 16-32%, about 18-40%, about 18-39%, about 18-35%, about 18-32%, about 20-40%, about 20-39%, about 20-35%, and about 15-32%.

[0044] The polyester film has an intrinsic viscosity of 0.66 or higher and 0.95 or lower. Here, intrinsic viscosity is a value measured by the method described in the evaluation method “(4) Intrinsic Viscosity” of the example described later. When the intrinsic viscosity is within this range, the entanglement of molecular chains increases, and resistance to deformation in the thickness direction, particularly puncture resistance, can be obtained. If the intrinsic viscosity is less than 0.66, the entanglement of molecular chains is insufficient, and sufficient drawing processability cannot be obtained. On the other hand, if the intrinsic viscosity exceeds 0.95, the discharge amount must be lowered due to the increase in filtration pressure during melt film formation, resulting in lower productivity. Intrinsic viscosity can be adjusted by the raw material used for melt film formation, and if the intrinsic viscosity of the film is to be increased, the intrinsic viscosity of the raw material used during film formation should be increased. Considering both the molecular chain entanglement effect and productivity, it is preferable that the intrinsic viscosity be 0.69 or higher and 0.88 or lower.

[0045] In order to more preferably exhibit the effects of the present invention, it is desirable that the thermal shrinkage rate at 150°C in the length direction and width direction of the polyester film be 3.5% or more and 14.0% or less. In a laminating process in which heat of about 150°C is applied, such as a secondary processing involving heating in which a polyester film is used in the substrate layer (1), for example, an extrusion laminating process in which molten resin is directly laminated onto the film, it is desirable that the thermal shrinkage rate at 150°C be 3.5% or more to suppress wrinkles during extrusion and laminating. On the other hand, if the thermal shrinkage rate of the temperature applied during laminating exceeds 14%, the film may cause problems by being excessively deformed during laminating due to thermal shrinkage during laminating. From the perspective of achieving compatibility between wrinkles and thermal deformation during lamination, it is desirable that the thermal shrinkage rate of the polyester film at 150°C in the length and width directions be 10% or less. To achieve a thermal shrinkage rate of 3.5% or more and 14.0% or less in the length and width directions, it is possible to control this by increasing the film area ratio to 12.25 times or more and then heat treating at a temperature of 160°C or more and 200°C or less. The thermal shrinkage rate of the polyester film at 150°C in the length and width directions is measured by the method described in the evaluation method of the example described later, “(11) Thermal shrinkage rate of the polyester film at 150°C in the length and width directions.”

[0046] From the perspective of more preferably exhibiting the effects of the present invention, the polyester film preferably has a melting point (endothermic melting peak temperature (Tm)) obtained from a differential scanning calorimeter of 235°C or higher. When the polyester film is used as a substrate layer for an outer casing material for a capacitor device, the thermally fusible resin layers are heat-sealed to form a container. Therefore, it is necessary to suppress the melting of the outer casing material caused by the heat of the heat sealing. If the endothermic melting peak temperature (Tm) is less than 235°C, it is necessary to lower the heating temperature when performing heat sealing, and as a result of the time required to form a container by heat sealing becoming longer, mass producibility may be poor. To make the endothermic melting peak temperature (Tm) 235°C or higher, it is most preferable to use homopolyester. Furthermore, from the perspective of the processability of the polyester film, it is preferable that the melting point be 320°C or lower. The melting point of the polyester film is the evaluation method of the examples described below. (9) Glass transition temperature (Tg), melting point (melting endothermic peak temperature (Tm)) is measured by the method described in “(9) Glass transition temperature (Tg), melting point (melting endothermic peak temperature (Tm)”.

[0047] In order to more preferably exhibit the effects of the present invention, the melting point of the polyester film is preferably 238°C or higher, more preferably 240°C or higher, and even more preferably 245°C or higher. In addition, the melting point of the polyester film is preferably 300°C or lower, more preferably 290°C or lower, and even more preferably 270°C or lower. Preferable ranges for the melting point of the polyester film include approximately 235 to 320 ℃, approximately 235 to 300 ℃, approximately 235 to 290 ℃, approximately 235 to 270 ℃, approximately 238 to 320 ℃, approximately 238 to 300 ℃, approximately 238 to 290 ℃, approximately 238 to 270 ℃, approximately 240 to 320 ℃, approximately 240 to 300 ℃, approximately 240 to 290 ℃, approximately 240 to 270 ℃, approximately 245 to 320 ℃, approximately 245 to 300 ℃, approximately 245 to 290 ℃, and approximately 245 to 270 ℃.

[0048] Polyester films are composed primarily of polyester. Polyester is a general term for polymer compounds in which the major bonds in the main chain are ester bonds. Polyester can typically be obtained by polycondensation reaction between a dicarboxylic acid or its derivative and a diol or its derivative, and electrolyte resistance can be obtained by composing the film primarily of polyester. Furthermore, "composing as a main component" as referred to in this disclosure indicates a proportion of 60 mass% or more and 100 mass% or less relative to the total object, and here refers to the proportion relative to the polyester film. Here, a dicarboxylic acid unit (structural unit) or a diol unit (structural unit) refers to a divalent organic group excluding the portion removed by polycondensation, and is represented by the following general formula.

[0049] Dicarboxylic acid unit (structural unit): -CO-R-CO-

[0050] Diol unit (structural unit): -O-R'-O-

[0051] (Here, R and R' are divalent organic groups. R and R' may be the same or different.)

[0052] Examples of diols or derivatives thereof that provide polyester, in addition to ethylene glycol, include aliphatic dihydroxy compounds such as 1,2-propanediol, 1,3-propanediol, 1,3-butanediol, 1,4-butanediol, 1,5-pentanediol, 1,6-hexanediol, and neopentyl glycol; polyoxyalkylene glycols such as diethylene glycol, polyethylene glycol, polypropylene glycol, and polytetramethylene glycol; alicyclic dihydroxy compounds such as 1,4-cyclohexanedimethanol and spiroglycol; aromatic dihydroxy compounds such as bisphenol A and bisphenol S; and derivatives thereof.

[0053] In addition, examples of dicarboxylic acids or derivatives thereof that provide polyester, other than terephthalic acid, include aromatic dicarboxylic acids such as isophthalic acid, phthalic acid, 2,6-naphthalenedicarboxylic acid, diphenyldicarboxylic acid, diphenylsulfonidicarboxylic acid, diphenoxyethanedicarboxylic acid, and 5-sodiumsulfonidicarboxylic acid; aliphatic dicarboxylic acids such as oxalic acid, succinic acid, adipic acid, sebacic acid, dimer acid, maleic acid, and fumaric acid; alicyclic dicarboxylic acids such as 1,4-cyclohexanedicarboxylic acid; oxycarboxylic acids such as parahydroxybenzoic acid; and derivatives thereof. Examples of derivatives of dicarboxylic acids include esters such as dimethyl terephthalate, diethyl terephthalate, 2-hydroxyethylmethyl terephthalate, dimethyl 2,6-naphthalenedicarboxylic acid, dimethyl isophthalate, dimethyl adipice, diethyl maleate, and dimethyl dimerate.

[0054] The polyester film may be composed of a single layer or a multilayer structure of two or more layers. In the case of a multilayer structure, a symmetrical configuration with respect to the central layer, such as B layer / A layer / B layer, is preferable from the perspective of suppressing warping after film formation. If warping occurs after film formation, handling performance may deteriorate during subsequent battery manufacturing processes. Furthermore, in the present disclosure, a five-layer configuration such as B / A / B / A / B is also acceptable. In the case of a multilayer structure, a three-layer stacked configuration of B / A / B is preferable from the perspective of warping after film formation. In the present disclosure, if a two-layer configuration such as A layer / B layer with different molecular orientations is used, warping may occur immediately after film formation. However, as long as it does not impede the effects of the present invention, an asymmetrical configuration such as a two-layer configuration of A / B is acceptable.

[0055] For the polyester film, it is desirable to have a dynamic friction coefficient μd of 0.3 or less on the die-side contact surface to improve drawability. By keeping the dynamic friction coefficient within the above range, the resistance to deformation during drawing molding is reduced, thereby improving processability. The dynamic friction coefficient of the polyester film is measured by the method described in “(12) Dynamic friction coefficient of polyester film” of the evaluation method of the example described below. Although there are no particular limitations to making the dynamic friction coefficient 0.3 or less, for example, it is desirable to have a layer containing 0.3 mass% or more and 5 mass% or less of inorganic particles and / or organic particles with an average particle size of 0.005 μm or more and 10 μm or less on the outermost layer. More preferably, it is 0.5 mass% or more and 3 mass% or less. However, if particles are added excessively, the elongation at break of the outer material may decrease. Therefore, it is important to add particles within a range that does not impede the effects of the present invention. In addition, as a particle in this disclosure, a particle with an average primary particle diameter of 0.005 μm or more is used. The particle size referred to here indicates the number average particle size and means the particle size observed within the cross-section of the film. If the shape is not a perfect circle, the value converted into a perfect circle of the same area is used as the particle size. Here, the number average particle size Dn can be obtained according to the following steps (1) to (4).

[0056] (1) First, a cross-section of the film is cut using a microtome without crushing it in the thickness direction, and a magnified image is obtained using a scanning electron microscope. At this time, the cutting is performed in a direction parallel to the film's TD direction (horizontal direction).

[0057] (2) Next, for each particle observed within the cross-section of the image above, the cross-sectional area S is calculated, and the particle diameter d is calculated using the following formula.

[0058] d=2×(S / π) 1 / 2

[0059] (3) Using the obtained particle size d and the number of resin particles n, Dn is calculated by the following formula.

[0060] Dn=Σd / n

[0061] However, Σd is the total number of particle diameters within the observation surface, and n is the total number of particles within the observation surface.

[0062] (4) The above (1) to (3) are carried out at five different locations, and the average value is taken as the number-average particle size. Then, 2500 μm per observation point 2 The above evaluation is performed in the above areas.

[0063] As inorganic particles, for example, wet and dry silica, colloidal silica, aluminum silicate, titanium oxide, calcium carbonate, calcium phosphate, barium sulfate, aluminum oxide, mica, kaolin, clay, etc. may be used. In addition, as organic particles, particles constituting styrene, silicon, acrylic acids, methacrylic acids, polyesters, divinyl compounds, etc. may be used. Among these, it is preferable to use inorganic particles such as wet and dry silica, alumina, and calcium carbonate, and particles constituting styrene, silicon, acrylic acid, methacrylic acid, polyesters, divinylbenzene, etc. In addition, two or more of these inorganic and organic particles may be used in combination. Furthermore, it is also preferable to perform surface roughness processing, such as embossing or sandblasting, on the film surface to control the maximum surface height.

[0064] The thickness of the polyester film is preferably 9㎛ or more and 30㎛ or less in terms of molding conformability and warping after molding when used as a substrate layer for an casing material for a capacitor device. Most preferably, it is 12㎛ or more and 28㎛ or less. Depending on the required drawing depth, if it is less than 9㎛, the moldability may be poor, and if it is 30㎛ or more, the rigidity may increase and warping may occur after molding.

[0065] For polyester films, it is also desirable to perform surface treatments such as corona treatment, plasma treatment, ozone treatment, or applying an anchor coating layer on the surface to improve adhesion with the adhesive layer. As a method for forming the anchor coating layer, examples include coating a resin onto the film surface (composite melt extrusion method, hot melt coating method, inline or offline coating method using solvents other than water, water-soluble and / or water-dispersible resins, etc.). Among these, an inline coating method in which a film-coating agent is applied to one side of the film before orientation crystallization is completed, stretched in at least one direction, and heat-treated to complete orientation crystallization is preferred in terms of uniform film formation and productivity. Furthermore, when applying the anchor coating layer, the resin is not particularly limited, but examples include acrylic resin, urethane resin, polyester resin, olefin resin, fluoropolymer resin, vinyl resin, chlorine resin, styrene resin, various graft resins, epoxy resin, silicone resin, etc., and a mixture of these resins may also be used. From the perspective of adhesion, it is preferable to use polyester resins, acrylic resins, or urethane resins. When using polyester resins as a water-based coating solution, water-soluble or water-dispersible polyester resins are used; however, to achieve such water solubility or water dispersibility, it is preferable to copolymerize compounds containing sulfonic acid bases or compounds containing carboxylic acid bases. Furthermore, when using acrylic resins as a water-based coating solution, it is necessary to ensure they are dissolved or dispersed in water, and surfactants (e.g., polyether compounds, but not limited to them) may be used as emulsifiers. Additionally, to further improve adhesion in the anchor coating layer, various crosslinking agents may be used in combination with the resin. Melamine-based, epoxy-based, and oxazoline-based resins are generally used as crosslinking agent resins.

[0066] The other layer may be, for example, a resin film formed by resin, or a film formed by applying resin. The resin film may be an unoriented film or an oriented film. Examples of oriented films include uniaxially oriented films and biaxially oriented films, and a biaxially oriented film is preferred. Examples of stretching methods for forming a biaxially oriented film include sequential biaxial stretching, inflation, and simultaneous biaxial stretching. Examples of methods for applying resin include roll coating, gravure coating, and extrusion coating.

[0067] As resins forming another layer, examples include polyamide, polyolefin, epoxy resin, acrylic resin, fluoropolymer, polyurethane, silicone resin, phenolic resin, etc., or modified products of these resins. In addition, the resin forming another layer may be a copolymer of these resins or a modified product of a copolymer. In addition, it may be a mixture of these resins.

[0068] Among these, polyamide can be preferably cited as a resin forming another layer. That is, when the substrate layer (1) of the present disclosure further includes another layer different from the polyester film, the substrate layer (1) is preferably a laminate of a polyester film and a polyamide film.

[0069] As polyamides, specifically, aliphatic polyamides such as nylon 6, nylon 66, nylon 610, nylon 12, nylon 46, and copolymers of nylon 6 and nylon 66, comprising constituent units derived from terephthalic acid and / or isophthalic acid, such as 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), aromatic polyamides such as polyamide MXD6 (polymethoxylylene adipamide); alicyclic polyamides such as polyamide PACM6 (polybis(4-aminocyclohexyl)methaneadipamide); Furthermore, examples of polyamides include polyamides copolymerized with lactam components or isocyanate components such as 4,4'-diphenylmethane-diisocyanate, polyesteramide copolymers or polyetheresteramide copolymers which are copolymers of copolymerized polyamides and polyesters or polyalkylene ether glycols; and polyamides such as these copolymers. These polyamides may be used as a single type or in combination of two or more types.

[0070] The polyamide film is preferably a stretched polyamide film, more preferably a stretched nylon film, and even more preferably a biaxially stretched nylon film.

[0071] In the case where the substrate layer (1) is composed of two or more layers, the substrate layer (1) may be a laminate in which each film is laminated with an adhesive or the like, or a laminate of two or more films formed by co-extruding resin. Additionally, a laminate of two or more resin films formed by co-extruding resin may be used as the substrate layer (1) in an unoriented state, or it may be used as the substrate layer (1) by uniaxial stretching or biaxial stretching.

[0072] For example, when the substrate layer (1) is a laminate of two or more resin films, it is preferable that the polyester film be located on the outermost layer of the substrate layer (1) for reasons such as the polyester being difficult to discolor when an electrolyte is attached to the surface.

[0073] When the substrate layer (1) is a laminate of two or more resin films, the two or more resin films may be laminated using an adhesive. When the substrate layer (1) is a laminate of two or more resin films, at least one layer must have the main axis orientation described above. As for the preferred adhesive, examples such as the adhesive exemplified in the adhesive layer (2) described later can be given. Furthermore, the method of laminating two or more resin films is not particularly limited, and known methods may be adopted. Examples include dry laminating, sandwich laminating, extrusion laminating, and thermal laminating, and preferably, dry laminating can be given as an example. When laminating by dry laminating, it is preferable to use a polyurethane adhesive as the adhesive. At this time, the thickness of the adhesive is, for example, about 2 to 5 μm. In addition, as explained regarding the polyester film, an anchor coating layer may be formed on the resin film used in the substrate layer and laminated. The anchor coating layer may be exemplified by the same adhesive as the adhesive layer (2) described later. At this time, the thickness of the anchor coating layer is, for example, about 0.01 to 1.0 μm.

[0074] In addition, at least one of the surface and interior of the substrate layer (1) may have additives such as a lubricant, flame retardant, anti-blocking agent, antioxidant, light stabilizer, tackifier, and antistatic agent. Only one type of additive may be used, or two or more types may be mixed and used.

[0075] In the present disclosure, from the perspective of improving the moldability of an outer casing for a capacitor device, it is preferable that a lubricant be present on the surface of the substrate layer (1). The lubricant is not particularly limited, but preferably, an amide-based lubricant may be an example. Specific examples of amide-based lubricants include, for example, saturated fatty acid amides, unsaturated fatty acid amides, substituted amides, methylolamides, saturated fatty acid bisamides, unsaturated fatty acid bisamides, fatty acid esteramides, aromatic bisamides, etc. Specific examples of saturated fatty acid amides include lauric acid amide, palmitate amide, stearate amide, behenate amide, hydroxystearate amide, etc. Specific examples of unsaturated fatty acid amides include oleic acid amide, erucic acid amide, etc. Specific examples of substituted amides include N-oleyl palmitate amide, N-stearyl stearate amide, N-stearyloleate amide, N-oleyl stearate amide, N-stearyl erucate amide, etc. In addition, specific examples of methylolamides include methylol stearate amide, etc. Specific examples of saturated fatty acid bisamides include methylenebisstearic acid amide, ethylenebiscapric acid amide, ethylenebislauric acid amide, ethylenebisstearic acid amide, ethylenebishydroxystearic acid amide, ethylenebisbehenic acid amide, hexamethylenebisstearic acid amide, hexamethylenebisbehenic acid amide, hexamethylenehydroxystearic acid amide, N,N'-distearyladipate amide, N,N'-distearylsebacate amide, etc. Specific examples of unsaturated fatty acid bisamides include ethylenebisoleic acid amide, ethylenebiserucate amide, methylenebisoleic acid amide, N,N'-dioleyladipate amide, N,N'-dioleylsebacate amide, etc. Specific examples of fatty acid esteramides include stearoamide ethyl stearate.In addition, specific examples of aromatic bisamides include m-xylylenebisstearamide, m-xylylenebishydroxystearate, N,N'-distearylisophthalamide, etc. The lubricant may be used as a single type or in combination of two or more types.

[0076] When a lubricant is present on the surface of the substrate layer (1), the amount present is not particularly limited, but preferably about 3 mg / m² 2 Ideally, 4 to 15 mg / m² 2 The degree, more preferably 5 to 14 mg / m² 2 Degrees can be cited as an example.

[0077] The lubricant present on the surface of the substrate layer (1) may be a lubricant exuded from the resin constituting the substrate layer (1), or a lubricant applied to the surface of the substrate layer (1).

[0078] Regarding the thickness of the substrate layer (1), it is not particularly limited as long as it functions as a substrate, but from the perspective of more preferably showing the effects of the invention of the present disclosure, it is preferably about 10 μm or more, more preferably about 15 μm or more. From the same perspective, it 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, even more preferably about 28 μm or less, and even more preferably about 25 μm or less. Examples of preferred ranges for the thickness of the substrate layer (1) include about 10 to 60 μm, about 10 to 50 μm, about 10 to 40 μm, about 10 to 30 μm, about 10 to 28 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, about 15 to 28 μm, and about 15 to 25 μm. When the substrate layer (1) is a laminate of two or more layers of resin film, the thickness of each layer of the resin film may preferably be about 2 to 25 μm.

[0079] [Adhesive layer (2)]

[0080] In the outer casing for a capacitor device of the present disclosure, the adhesive layer (2) is a layer installed between the substrate layer (1) and the barrier layer (3) as needed for the purpose of increasing the adhesion between the substrate layer (1) and the barrier layer (3).

[0081] The adhesive layer (2) is formed by an adhesive capable of bonding the substrate layer (1) and the barrier layer (3). The adhesive used to form the adhesive layer (2) is not limited, but can be any of the following: chemical reaction type, solvent volatile type, heat melting type, heat pressing type, etc. Additionally, it can 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. Additionally, the adhesive layer (2) can be a single layer or a multi-layer.

[0082] Examples of adhesive components included in the adhesive include, specifically, polyesters such as polyethylene terephthalate, polybutylene terephthalate, polyethylene naphthalate, polybutylene naphthalate, polyethylene isophthalate, and copolymerized polyester; polyethers; polyurethanes; epoxy resins; phenolic resins; polyamides such as nylon 6, nylon 66, nylon 12, and copolymerized polyamides; polyolefin-based resins such as polyolefins, cyclic polyolefins, acid-modified polyolefins, and acid-modified cyclic polyolefins; polyvinyl acetate; cellulose; (meth)acrylic resins; polyimide; polycarbonates; amino resins such as urea resin and melamine resin; rubbers such as chloroprene rubber, nitrile rubber, and styrene-butadiene rubber; and silicone resins. These adhesive components may be used individually or in combination of two or more types. Among these adhesive components, polyurethane adhesives are preferably exemplified. Additionally, the adhesive strength of the resin serving as these adhesive components can be increased by using a suitable curing agent in combination. Depending on the functional groups of the adhesive components, the curing agent is selected from polyisocyanates, multifunctional epoxy resins, oxazoline-containing polymers, polyamine resins, acid anhydrides, etc.

[0083] As a polyurethane adhesive, for example, there is a polyurethane adhesive comprising a first agent containing a polyol compound and a second agent containing an isocyanate compound. Preferably, an example of a two-component curing type polyurethane adhesive can be given in which a polyol such as a polyester polyol, a polyether polyol, and an acrylic polyol is used as the first agent and an aromatic or aliphatic polyisocyanate is used as the second agent. In addition, as a polyurethane adhesive, for example, there is a polyurethane adhesive comprising a polyurethane compound in which a polyol compound and an isocyanate compound have been reacted beforehand and an isocyanate compound. In addition, as a polyurethane adhesive, for example, there is a polyurethane adhesive comprising a polyurethane compound in which a polyol compound and an isocyanate compound have been reacted beforehand and a polyol compound. Furthermore, as a polyurethane adhesive, for example, there is a polyurethane adhesive in which a polyurethane compound in which a polyol compound and an isocyanate compound have been reacted beforehand is cured by reacting it with moisture such as air. As the polyol compound, it is preferable to use a polyester polyol having hydroxyl groups in the side chain in addition to the hydroxyl groups at the terminals of the repeating unit. As the second agent, examples of aliphatic, alicyclic, aromatic, or aromatic aliphatic isocyanate compounds may be used. Examples of isocyanate compounds include hexamethylene diisocyanate (HDI), xylylene diisocyanate (XDI), isophorone diisocyanate (IPDI), hydrogenated XDI (H6XDI), hydrogenated MDI (H12MDI), trilene diisocyanate (TDI), diphenylmethane diisocyanate (MDI), and naphthalene diisocyanate (NDI). In addition, examples of polyfunctional isocyanate modified compounds derived from one or more of these diisocyanates may be used. Furthermore, a polymer (e.g., a trimer) may be used as the polyisocyanate compound. Examples of such polymers include adducts, biurets, and nurates.Since the adhesive layer (2) is formed by a polyurethane adhesive, excellent electrolyte resistance is imparted to the outer material for the capacitor device, so that the peeling of the substrate layer (1) is suppressed even when the electrolyte is attached to the side.

[0084] Additionally, the adhesive layer (2) may contain other components as long as they do not impair adhesion, and may contain coloring agents, thermoplastic elastomers, tackifiers, fillers, etc. Since the adhesive layer (2) contains a coloring agent, the outer material for the capacitor device can be colored. Known materials such as pigments and dyes may be used as coloring agents. Additionally, only one type of coloring agent may be used, or two or more types may be mixed and used.

[0085] 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, quinaclidon-based, anthraquinone-based, black photochromic, indigothioindigo-based, perinone-perylene-based, isoindolenin-based, and benzimidazolone-based pigments, and examples of inorganic pigments include carbon black-based, titanium oxide-based, cadmium-based, lead-based, chromium oxide-based, and iron-based pigments, and in addition, fine powder of mica and fish scales may be used as examples.

[0086] Among coloring agents, carbon black is preferred, for example, to make the exterior of an casing for a capacitor black.

[0087] The average particle diameter of the pigment is not particularly limited, for example, to about 0.05 to 5 μm, preferably about 0.08 to 2 μm. In addition, the average particle diameter of the pigment is the median diameter measured by a laser diffraction / scattering particle diameter distribution measuring device.

[0088] The pigment content in the adhesive layer (2) is not particularly limited when the outer material for the capacitor device is colored, and is, for example, about 5 to 60 mass%, preferably 10 to 40 mass%.

[0089] The thickness of the adhesive layer (2) is not particularly limited as long as it allows the substrate layer (1) and the barrier layer (3) to be bonded, but for example, it is about 1 μm or more and about 2 μm or more. Also, the thickness of the adhesive layer (2) is, for example, about 10 μm or less and about 5 μm or less. Additionally, regarding the preferred range of the thickness of the adhesive layer (2), examples include about 1 to 10 μm, about 1 to 5 μm, about 2 to 10 μm, and about 2 to 5 μm.

[0090] [Color layer]

[0091] The coloring layer is a layer installed as needed between the substrate layer (1) and the barrier layer (3) (not shown). In the case of having an adhesive layer (2), the coloring layer may be formed between the substrate layer (1) and the adhesive layer (2), or between the adhesive layer (2) and the barrier layer (3). Additionally, the coloring layer may be formed on the outer side of the substrate layer (1). By forming the coloring layer, the outer material for the capacitor device can be colored.

[0092] The colored layer can be formed, for example, by applying an ink containing a coloring agent to the surface of the substrate layer (1) or the surface of the barrier layer (3). Known coloring agents such as pigments and dyes may be used. Additionally, only one type of coloring agent may be used, or two or more types may be mixed and used.

[0093] Specific examples of coloring agents included in the coloring layer are those identical to those exemplified in the [adhesive layer (2)] column.

[0094] [Barrier layer (3)]

[0095] In the outer material for a capacitor device, the barrier layer (3) is a layer that at least prevents moisture from entering.

[0096] As a barrier layer (3), examples include a metal foil having barrier properties, a deposited film, a resin layer, etc. Examples of the deposited film include a metal deposited film, an inorganic oxide deposited film, a carbon-containing inorganic oxide deposited film, etc. Examples of the resin layer include a fluorine-containing resin such as polyvinylidene chloride, a polymer mainly composed of chlorotrifluoroethylene (CTFE), a polymer mainly composed of tetrafluoroethylene (TFE), a polymer having fluoroalkyl groups, and a polymer mainly composed of fluoroalkyl units, and an ethylene vinyl alcohol copolymer. In addition, as a barrier layer (3), a resin film having at least one layer among these deposited films and resin layers can also be an example. The barrier layer (3) may be installed in multiple layers. It is preferable that the barrier layer (3) includes a layer composed of a metal material. As for the metal material constituting the barrier layer (3), specifically, aluminum alloy, stainless steel, titanium steel, steel, etc., can be used as examples, and when used as a metal foil, it is preferable to include at least one of an aluminum alloy foil and a stainless steel foil.

[0097] From the perspective of improving the formability of the outer casing for a capacitor device, it is more preferable that the aluminum alloy foil be a soft aluminum alloy foil composed of, for example, an annealed aluminum alloy, and from the perspective of further improving formability, it is preferable that the aluminum alloy foil be an aluminum alloy foil containing iron. In the aluminum alloy foil containing iron (100 mass%), the iron content is preferably 0.1 to 9.0 mass%, and more preferably 0.5 to 2.0 mass%. By having an iron content of 0.1 mass% or more, an outer casing for a capacitor device having better formability can be obtained. By having an iron content of 9.0 mass% or less, an outer casing for a capacitor device having better flexibility can be obtained. As for soft aluminum alloy foil, there is, for example, aluminum alloy foil 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. Additionally, silicon, magnesium, copper, manganese, etc. may be added as needed. Furthermore, softening can be performed by annealing treatment, etc.

[0098] In addition, examples of stainless steel foil include austenitic, ferritic, austenitic-ferritic, martensitic, and precipitation-hardened stainless steel foils. From the perspective of providing an outer casing for capacitor devices with excellent formability, it is preferable that the stainless steel foil be composed of austenitic stainless steel.

[0099] Specific examples of austenitic stainless steel constituting the stainless steel sheet include SUS304, SUS301, SUS316L, etc., and among these, SUS304 is particularly preferred.

[0100] In the case of a metal foil, the thickness of the barrier layer (3) should function as a barrier layer that suppresses the intrusion of moisture, and is, for example, about 9 to 200 μm. The thickness of the barrier layer (3) is preferably 100 μm or less, more preferably about 85 μm or less. In addition, the thickness of the barrier layer (3) is preferably about 25 μm or more, more preferably 30 μm or more. In addition, examples of a preferred range for the thickness of the barrier layer (3) include about 25 to 100 μm, about 25 to 85 μm, about 30 to 100 μm, and about 30 to 85 μm. When the barrier layer (3) is composed of an aluminum alloy foil, the aforementioned range is particularly preferred. In addition, particularly when the barrier layer (3) is composed of stainless steel foil, the thickness of the stainless steel foil is preferably about 60 μm or less, more preferably about 50 μm or less, even more preferably about 40 μm or less, even more preferably about 30 μm or less, and particularly preferably about 25 μm or less. In addition, the thickness of the stainless steel foil is preferably about 10 μm or more, more preferably about 15 μm or more. In addition, examples of a preferred range 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.

[0101] In addition, if the barrier layer (3) is a metal foil, it is preferable to have a corrosion-resistant film on at least the side opposite to the substrate layer to prevent dissolution or corrosion. The barrier layer (3) may have a corrosion-resistant film on both sides. Here, a corrosion-resistant film refers to a thin film that provides corrosion resistance (e.g., acid resistance, alkali resistance) to the barrier layer by performing a corrosion prevention treatment on the surface of the barrier layer, such as a hydrothermal modification treatment like boehmite treatment, a chemical treatment, anodizing treatment, plating treatment such as nickel or chromium, or applying a coating agent. Specifically, the corrosion-resistant film refers to a film that improves the acid resistance of the barrier layer (acid-resistant film), a film that improves the alkali resistance of the barrier layer (alkali-resistant film), etc. As for the treatment to form the corrosion-resistant film, one type may be performed, or two or more types may be combined. In addition, it may be multi-layered rather than just a single layer. In addition, among these treatments, hydrothermal modification treatment and anodic oxidation treatment are treatments that dissolve the surface of the metal foil with a treatment agent to form a metal compound with excellent corrosion resistance. Also, these treatments may be included in the definition of chemical treatment. In addition, if the barrier layer (3) is equipped with a corrosion-resistant film, the barrier layer (3) is formed by including the corrosion-resistant film.

[0102] The corrosion-resistant film prevents delamination between the barrier layer (e.g., aluminum alloy foil) and the substrate layer during the molding of an outer casing for a capacitor device, prevents dissolution and corrosion of the barrier layer surface caused by hydrogen fluoride generated by the reaction between the electrolyte and moisture, and particularly prevents the 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 (wetting) of the barrier layer surface and exhibits the effect of preventing delamination between the substrate layer and the barrier layer during heat sealing and during molding.

[0103] Various corrosion-resistant films formed by phosphating treatment are known, and examples mainly include corrosion-resistant films comprising at least one of phosphates, chromates, fluorides, triazinethiol compounds, and rare earth oxides. Phosphating treatments using phosphates and chromates include, for example, 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 phosphate, acetylacetate chromate, chromium chloride, and potassium chromium sulfate. In addition, examples of phosphorus compounds used in these treatments include sodium phosphate, potassium phosphate, ammonium phosphate, and polyphosphoric acid. Furthermore, examples of chromate treatments include etching chromate treatment, electrolytic chromate treatment, and coating chromate treatment, and coating chromate treatment is preferred. This coating-type chromate treatment is a process in which, first, at least the inner layer side of a barrier layer (e.g., aluminum alloy foil) is degreased using a well-known treatment method such as alkaline immersion, electrolytic cleaning, acid cleaning, electrolytic acid cleaning, or acid activation; and subsequently, a treatment solution comprising metal phosphate salts such as Cr (chromium) phosphate, Ti (titanium) phosphate, Zr (zirconium) phosphate, and Zn (zinc) phosphate, and a mixture of these metal salts, or a treatment solution comprising non-metallic phosphate salts and a mixture of these non-metallic salts, or a mixture of these and synthetic resin, is applied to the degreased surface using a well-known coating method such as roll coating, intaglio printing, or immersion, and then dried. For the treatment solution, various solvents such as water, alcohol-based solvents, hydrocarbon-based solvents, ketone-based solvents, ester-based solvents, and ether-based solvents may be used, and water is preferred.In addition, examples of resin components used at this time include polymers such as phenolic resins or acrylic resins, and examples include chromate treatment using an aminoated phenolic polymer having repeating units represented by the following general formulas (1) to (4). Furthermore, in the above aminoated phenolic polymer, the repeating unit represented by the following general formulas (1) to (4) may be included as a single type or 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 derivatives such as sodium salts, ammonium salts, or amine salts thereof. In particular, derivatives of polyacrylic acid such as ammonium salts, sodium salts, or amine salts of polyacrylic acid are preferred. In the present disclosure, polyacrylic acid refers to a polymer of acrylic acid. In addition, the acrylic resin is preferably a copolymer of acrylic acid and a dicarboxylic acid or a dicarboxylic acid anhydride, and is also preferably an ammonium salt, sodium salt, or amine salt of a copolymer of acrylic acid and a dicarboxylic acid or a dicarboxylic acid anhydride. The acrylic resin may be used as a single type or as a mixture of two or more types.

[0104]

[0105]

[0106]

[0107]

[0108] In general formulas (1) to (4), X represents a hydrogen atom, a hydroxyl group, an alkyl group, a hydroxyalkyl group, an allyl group, or a benzyl group. Also, R 1 and R 2 Each represents a hydroxyl group, an alkyl group, or a hydroxyalkyl group, and is the same or different. In general formulas (1) to (4), X, R 1 and R 2As for the alkyl group represented by, for example, there are straight-chain or branched-chain alkyl groups having 1 to 4 carbon atoms, such as methyl, ethyl, n-propyl, isopropyl, n-butyl, isobutyl, and tert-butyl groups. In addition, X, R 1 and R 2 As the hydroxyalkyl group represented by, for example, there are straight-chain or branched-chain alkyl groups having 1 to 4 carbon atoms substituted with one hydroxyl group, such as hydroxymethyl group, 1-hydroxyethyl group, 2-hydroxyethyl group, 1-hydroxypropyl group, 2-hydroxypropyl group, 3-hydroxypropyl group, 1-hydroxybutyl group, 2-hydroxybutyl group, 3-hydroxybutyl group, 4-hydroxybutyl group. In general formulas (1) to (4), X, R 1 and R 2 The alkyl group and the hydroxyalkyl group represented by may each be the same or different. In general formulas (1) to (4), X is preferably a hydrogen atom, a hydroxyl group, or a hydroxyalkyl group. The number average molecular weight of the aminified phenol polymer having repeating units represented by general formulas (1) to (4) is preferably, for example, about 5 million to 1 million, and more preferably about 1,000 to 20,000. The aminified phenol polymer is, for example, prepared by polycondensing a phenol compound or a naphthol compound with formaldehyde to produce a polymer consisting of repeating units represented by general formula (1) or general formula (3), and then formaldehyde and amine (R 1 R 2 Using NH) for the functional group (-CH2NR 1 R 2 It is manufactured by introducing ) into the polymer obtained above. The aminified phenol polymer is used alone or in a mixture of two or more types.

[0109] Another example of a corrosion-resistant film 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 include phosphoric acid or a phosphate, and a crosslinking agent for crosslinking the polymer. In the rare earth element oxide sol, fine particles of the rare earth element oxide (e.g., particles with an average particle size of 100 nm or less) are dispersed in a liquid dispersion medium. Examples of rare earth element oxides include cerium oxide, yttrium oxide, neodymium oxide, and lanthanum oxide, and cerium oxide is preferred from the viewpoint of further improving adhesion. The rare earth element oxide included in the corrosion-resistant film may be used as a single type or in combination of two or more types. As a liquid dispersion medium for the rare earth element oxide sol, various solvents such as water, alcohol-based solvents, hydrocarbon-based solvents, ketone-based solvents, ester-based solvents, and ether-based solvents may be used, and water is preferred. As a cationic polymer, for example, polyethyleneimine, an ionic polymer complex composed of polyethyleneimine and a polymer having a carboxylic acid, a primary amine graft acrylic resin formed by graft polymerizing a primary amine onto an acrylic main frame, polyallylamine or its derivative, and aminoated phenol are preferred. In addition, as an anionic polymer, it is preferred to be poly(meth)acrylic acid or its salt, or a copolymer having (meth)acrylic acid or its salt as a main component. In addition, the crosslinking agent is preferably at least one selected from the group consisting of a compound having a functional group among an isocyanate group, a glycidyl group, a carboxyl group, or an oxazoline group, and a silane coupling agent. In addition, it is preferable that the above phosphoric acid or phosphate is a condensed phosphoric acid or a condensed phosphate.

[0110] An example of a corrosion-resistant film is one formed by applying 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 performing a baking treatment at 150°C or higher.

[0111] If necessary, the corrosion-resistant film may be in a laminated structure in which at least one of a cationic polymer and an anionic polymer is further laminated. Examples of cationic polymers and anionic polymers include those described above.

[0112] In addition, the composition of the corrosion-resistant film can be analyzed using, for example, time-of-flight secondary ion mass spectrometry.

[0113] Regarding the amount of corrosion-resistant film formed on the surface of the barrier layer (3) during the chemical treatment, there is no particular limitation, but for example, if a coating-type chromate treatment is performed, 1m of the surface of the barrier layer (3) 2 It is preferable that the sugar, chromium oxide compound is contained in an amount of about 0.5 to 50 mg, preferably about 1.0 to 40 mg, in terms of chromium equivalent; the phosphorus compound is contained in an amount of about 0.5 to 50 mg, preferably about 1.0 to 40 mg, in terms of phosphorus equivalent; and the amino phenol polymer is contained in an amount of about 1.0 to 200 mg, preferably about 5.0 to 150 mg.

[0114] Although the thickness of the corrosion-resistant film is not particularly limited, examples can be given that, in terms of the film's cohesiveness or the adhesion of the barrier layer or the heat-sealable resin layer, it 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. Furthermore, the thickness of the corrosion-resistant film can be measured by observation using a transmission electron microscope, or by a combination of observation using a transmission electron microscope and energy-dispersive X-ray spectroscopy or electron beam energy loss spectroscopy. By analyzing the composition of the corrosion-resistant film using time-of-flight secondary ion mass spectrometry, for example, secondary ions composed of Ce, P, and O (e.g., Ce2PO4 ＋ , CePO4 - At least one of the following) or, for example, a secondary ion composed of Cr, P, and O (for example, CrPO2 ＋ , CrPO4 - A peak originating from at least one of the following is detected.

[0115] Chemical conversion treatment is performed by applying a solution containing a compound used for forming a corrosion-resistant film to the surface of a barrier layer by bar coating, roll coating, gravure coating, immersion, etc., and then heating the barrier layer to a temperature of approximately 70 to 200°C. Additionally, prior to performing chemical conversion treatment on the barrier layer, the barrier layer may be subjected to degreasing treatment by alkaline immersion, electrolytic cleaning, acid cleaning, or electrolytic acid cleaning. By performing degreasing treatment in this manner, it becomes possible to perform chemical conversion treatment on the surface of the barrier layer more efficiently. Furthermore, by using an acid degreasing agent in which a fluorine-containing compound is dissolved in an inorganic acid for the degreasing treatment, it is possible to form a fluoride of the passivated metal in addition to the degreasing effect of the metal foil, and in such cases, only the degreasing treatment may be performed.

[0116] [Thermal fusible resin layer (4)]

[0117] In the outer casing for a capacitor device of the present disclosure, the heat-fusible resin layer (4) corresponds to the innermost layer and is a layer (sealant layer) that performs the function of sealing capacitor device elements by heat-fusing the heat-fusible resin layers together when assembling the capacitor device.

[0118] Regarding the resin constituting the heat-fusible resin layer (4), it is not particularly limited to those that are heat-fusible, but examples include polyolefins such as homo or block-type polypropylene, resins containing a polyolefin backbone such as cyclic polyolefin, polyesters such as polyethylene terephthalate and polybutylene terephthalate, polyacetals, acrylic resins, copolymers of polymethylpentene and its α-olefins, 6-nylon, 66-nylon, polyvinylidene chloride, polyphenylene sulfide, acetylcellulose, ETFE, PCTFE, PFA, FEP, fluorinated resins, and furthermore, resins modified by maleic anhydride or acrylic acid (e.g., acid-modified polyolefins). In addition, these resins may be of one type or two or more types. Whether the resin constituting the heat-fusible resin layer (4) contains a polyolefin framework can be analyzed, for example, by infrared spectroscopy, gas chromatography-mass spectrometry, etc. Additionally, when the resin constituting the heat-fusible resin layer (4) is analyzed by infrared spectroscopy, it is preferable that a peak originating from maleic anhydride is detected. For example, when maleic anhydride-modified polyolefin is measured by infrared spectroscopy, a wavenumber of 1760 cm⁻¹ is obtained. -1 Nearby and Watchtower 1780cm -1 A peak of maleic anhydride origin is detected in the vicinity. When the heat-fusible resin layer (4) is a layer composed of maleic anhydride-modified polyolefin, a peak of maleic anhydride origin is detected when measured by infrared spectroscopy. However, if the degree of acid modification is low, the peak may become smaller and not be detected. In that case, it can be analyzed by nuclear magnetic resonance spectroscopy.

[0119] Examples of polyolefins include, specifically, 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. In the case of copolymers, the polyolefin resin may be a block copolymer or a random copolymer. These polyolefin resins may be used as a single type or in combination of two or more types.

[0120] In addition, the polyolefin may be a cyclic polyolefin. A cyclic polyolefin is a copolymer of an olefin and a cyclic monomer, and examples of olefins that are constituent monomers of the cyclic polyolefin include ethylene, propylene, 4-methyl-1-pentene, styrene, butadiene, isoprene, etc. In addition, examples of cyclic monomers that are constituent monomers of the cyclic polyolefin include cyclic alkenes such as norbornene; cyclic dienes such as cyclopentadiene, dicyclopentadiene, cyclohexadiene, norbornene, etc. Among these, preferably, cyclic alkenes, and more preferably norbornene, can be cited as examples.

[0121] Acid-modified polyolefin is a polymer modified by block polymerization or graft polymerization of a polyolefin with an acid component. As the polyolefin to be acid-modified, the above-mentioned polyolefin, a copolymer formed by copolymerizing a polar molecule such as acrylic acid or methacrylic acid with the above-mentioned polyolefin, or a polymer such as a cross-linked polyolefin may also be used. In addition, as the acid component used for acid modification, examples include carboxylic acids such as maleic acid, acrylic acid, itaconic acid, crotonic acid, maleic anhydride, and itaconic anhydride, or their anhydrides.

[0122] Acid-modified polyolefins may also be acid-modified cyclic polyolefins. Acid-modified cyclic polyolefins are polymers obtained by copolymerizing a portion of the monomers constituting a cyclic polyolefin instead of an acid component, or by block polymerizing or graft polymerizing an acid component with respect to a cyclic polyolefin. The cyclic polyolefins undergoing acid modification are the same as those described above. Furthermore, the acid component used for acid modification is the same as the acid component used for modifying the polyolefins described above.

[0123] Examples of desirable acid-modified polyolefins include polyolefins modified with a carboxylic acid or its anhydride, polypropylene modified with a carboxylic acid or its anhydride, maleic anhydride-modified polyolefins, and maleic anhydride-modified polypropylene.

[0124] By forming the heat-fusible resin layer (4) from the above resins, such as a block-type polypropylene maleic anhydride modified resin, a polymethylpentene or its α-olefin copolymer maleic anhydride modified resin, a cyclic polyolefin maleic anhydride modified resin, a fluorine-based resin such as ETFE, PCTFE, PFA, FEP, polyethylene terephthalate, polybutylene terephthalate, etc., the outer casing (10) for a storage device of the present disclosure can exhibit high sealing strength in a high-temperature environment when applied to applications requiring heat resistance, such as batteries used at high temperatures (e.g., 80°C or higher). In addition, polyethylene terephthalate and polybutylene terephthalate may be stretched or unstretched, and may also contain an elastomer.

[0125] It is preferable that the polybutylene terephthalate film further comprises an elastomer in addition to polybutylene terephthalate. The elastomer serves to increase the flexibility of the polybutylene terephthalate film while ensuring its durability in high-temperature environments. Preferred elastomers include at least one thermoplastic elastomer selected from polyester, polyamide, polyurethane, polyolefin, polystyrene, polyether, and acrylic types, or thermoplastic elastomers that are copolymers thereof. More preferably, examples include a thermoplastic elastomer composed of a block copolymer of polybutylene terephthalate and polyether, or a thermoplastic elastomer composed of an α-olefin copolymer of polymethylpentene. In the heat-fusible resin layer (4), the content of the elastomer is not particularly limited as long as it is sufficient to increase flexibility while ensuring excellent heat resistance and sealing properties of the heat-fusible resin layer (4), for example, about 0.1 mass% or more, preferably about 0.5 mass% or more, more preferably about 1.0 mass% or more, and even more preferably about 3.0 mass% or more. In addition, the above content is, for example, about 10.0 mass% or less, about 8.0 mass% or less, about 5.0 mass% or less, etc. Preferred ranges of the above content include approximately 0.1 to 10.0 mass%, approximately 0.1 to 8.0 mass%, approximately 0.1 to 5.0 mass%, approximately 0.5 to 10.0 mass%, approximately 0.5 to 8.0 mass%, approximately 0.5 to 5.0 mass%, approximately 1.0 to 10.0 mass%, approximately 1.0 to 8.0 mass%, approximately 1.0 to 5.0 mass%, approximately 3.0 to 10.0 mass%, approximately 3.0 to 8.0 mass%, and approximately 3.0 to 5.0 mass%.

[0126] The heat-fusible resin layer (4) may be formed by a single type of resin alone, or by a blending polymer that combines two or more types of resins. Additionally, the heat-fusible resin layer (4) may be formed as a single layer, but may also be formed as two or more layers by the same or different resins.

[0127] Additionally, the heat-fusible resin layer (4) may include a lubricant, etc., as needed. If the heat-fusible resin layer (4) includes a lubricant, the moldability of the outer material for the capacitor device can be improved. As for the lubricant, there are no particular restrictions, and known lubricants may be used. The lubricant may be used as a single type, or two or more types may be used in combination.

[0128] As for the lubricant, it is not particularly limited, but preferably, an amide-based lubricant can be cited as an example. Specific examples of the lubricant include those exemplified in the substrate layer (1). The lubricant may be used as a single type or in combination of two or more types.

[0129] When a lubricant is present on the surface of the heat-fusible resin layer (4), the amount present is not particularly limited, but from the perspective of improving the moldability of the outer material for the capacitor device, it is preferably 10 to 50 mg / m² 2 The amount, more preferably 15 to 40 mg / m² 2 Degrees can be cited as an example.

[0130] The lubricant present on the surface of the heat-fusible resin layer (4) may be a lubricant exuded from the resin constituting the heat-fusible resin layer (4), or a lubricant applied to the surface of the heat-fusible resin layer (4).

[0131] In addition, the thickness of the heat-fusible resin layer (4) is not particularly limited as long as the heat-fusible resin layers heat-fusify each other to perform the function of sealing the capacitor device element, but for example, it is about 100 μm or less, preferably about 85 μm or less, more preferably about 15 to 85 μm. And, for example, when the thickness of the adhesive layer (5) described later is 10 μm or more, the thickness of the heat-fusible resin layer (4) can be exemplified as preferably about 85 μm or less, more preferably about 15 to 45 μm, and for example, when the thickness of the adhesive layer (5) described later is less than 10 μm or when the adhesive layer (5) is not installed, the thickness of the heat-fusible resin layer (4) can be exemplified as preferably about 20 μm, more preferably about 35 to 85 μm.

[0132] [Adhesive layer (5)]

[0133] In the outer casing for a capacitor device of the present disclosure, the adhesive layer (5) is a layer installed between the barrier layer (3) (or corrosion-resistant film) and the heat-fusible resin layer (4) as needed to firmly bond them.

[0134] The adhesive layer (5) is formed by a resin capable of bonding the barrier layer (3) and the heat-fusible resin layer (4). As the resin used to form the adhesive layer (5), for example, the same adhesive as the adhesive exemplified in the adhesive layer (2) can be used. Furthermore, in terms of strongly bonding the adhesive layer (5) and the heat-fusible resin layer (4), it is preferable that the resin used to form the adhesive layer (5) contains a polyolefin backbone, and examples include the polyolefin and acid-modified polyolefin exemplified in the aforementioned heat-fusible resin layer (4). Meanwhile, in terms of strongly bonding the barrier layer (3) and the adhesive layer (5), it is preferable that the adhesive layer (5) contains an acid-modified polyolefin. Examples of acid-modified components include dicarboxylic acids such as maleic acid, itaconic acid, succinic acid, and adipic acid, their anhydrides, acrylic acid, and methacrylic acid, but maleic anhydride is most preferable in terms of ease of modification and versatility. In addition, from the perspective of heat resistance of the outer material for the capacitor device, it is preferable that the olefin component be a polypropylene-based resin, and it is most preferable that the adhesive layer (5) include maleic anhydride-modified polypropylene.

[0135] Whether the resin constituting the adhesive layer (5) contains a polyolefin framework can be analyzed, for example, by infrared spectroscopy, gas chromatography-mass spectrometry, etc., and the analysis method is not particularly required. In addition, whether the resin constituting the adhesive layer (5) contains an acid-modified polyolefin, for example, when maleic anhydride-modified polyolefin is measured by infrared spectroscopy, the wavenumber is 1760 cm -1 Nearby and Watchtower 1780cm -1 A peak derived from maleic anhydride is detected in the vicinity. However, if the degree of acid transformation is low, the peak may become small and not be detected. In such cases, analysis is possible using nuclear magnetic resonance spectroscopy.

[0136] In addition, from the perspective of ensuring durability, such as heat resistance or melt resistance, of the outer material for the capacitor device, and moldability while keeping the thickness thin, it is more preferable that the adhesive layer (5) be a cured product of a resin composition containing an acid-modified polyolefin and a curing agent. As for the acid-modified polyolefin, the above-mentioned example may be exemplified.

[0137] Additionally, the adhesive layer (5) is preferably a cured product of a resin composition comprising at least one selected from the group consisting of an acid-modified polyolefin, a compound having an isocyanate group, a compound having an oxazoline group, and a compound having an epoxy group, and is particularly preferably a cured product of a resin composition comprising at least one selected from the group consisting of an acid-modified polyolefin, a compound having an isocyanate group, and a compound having an epoxy group. Additionally, the adhesive layer (5) is preferably a cured product of a resin composition comprising at least one selected from the group consisting of polyurethane, polyester, and epoxy resin, and is more preferably a cured product of polyurethane and epoxy resin. As for the polyester, for example, an ester resin produced by the reaction of an epoxy group and a maleic anhydride group, or an amide ester resin produced by the reaction of an oxazoline group and a maleic anhydride group is preferred. And, if unreacted material of a curing agent such as a compound having an isocyanate group, a compound having an oxazoline group, or an epoxy resin remains in the adhesive layer (5), the presence of unreacted material can be confirmed by a method selected from, for example, infrared spectroscopy, Raman spectroscopy, time-of-flight secondary ion mass spectrometry (TOF-SIMS).

[0138] In addition, to further enhance the adhesion between the barrier layer (3) and the adhesive layer (5), the adhesive layer (5) is preferably a cured product of a resin composition comprising at least one curing agent selected from the group consisting of oxygen atoms, heterocyclic rings, C=N bonds, and COC bonds. Examples of curing agents having heterocyclic rings include curing agents having oxazoline groups and curing agents having epoxy groups. Examples of curing agents having C=N bonds include curing agents having oxazoline groups and curing agents having isocyanate groups. Examples of curing agents having COC bonds include curing agents having oxazoline groups and curing agents having epoxy groups. That the adhesive layer (5) is a cured product of a resin composition containing these curing agents can be confirmed by methods such as gas chromatography-mass spectrometry (GCMS), infrared spectroscopy (IR), time-of-flight second-order ion mass spectrometry (TOF-SIMS), and X-ray photoelectron spectroscopy (XPS).

[0139] Compounds having isocyanate groups are not particularly limited, but from the perspective of effectively increasing the adhesion between the barrier layer (3) and the adhesive layer (5), polyfunctional isocyanate compounds are preferably examples. Polyfunctional isocyanate compounds are not particularly limited as long as they are compounds having two or more isocyanate groups. Specific examples of polyfunctional isocyanate-based curing agents include pentane diisocyanate (PDI), isophorone diisocyanate (IPDI), hexamethylene diisocyanate (HDI), trilene diisocyanate (TDI), diphenylmethane diisocyanate (MDI), polymerized or nurate-ized versions thereof, mixtures thereof, or copolymers of other polymers. Additionally, adducts, biurets, and isocyanurates may be examples.

[0140] In the adhesive layer (5), the content of the compound having an isocyanate group is preferably in the range of 0.1 to 50 mass% in the resin composition constituting the adhesive layer (5), and more preferably in the range of 0.5 to 40 mass%. This allows the adhesion between the barrier layer (3) and the adhesive layer (5) to be effectively increased.

[0141] Compounds having an oxazoline group are not particularly limited as long as they have an oxazoline backbone. Specific examples of compounds having an oxazoline group include those having a polystyrene main chain or an acrylic main chain. In addition, commercially available products include, for example, the Epocross series manufactured by Nippon Shokubai.

[0142] In the adhesive layer (5), the ratio of the compound having an oxazoline group is preferably in the range of 0.1 to 50 mass% in the resin composition constituting the adhesive layer (5), and more preferably in the range of 0.5 to 40 mass%. This allows the adhesion between the barrier layer (3) and the adhesive layer (5) to be effectively increased.

[0143] Examples of compounds having epoxy groups include epoxy resins. As for the epoxy resin, any known epoxy resin can be used without particular limitation, provided that it is a resin capable of forming a cross-linked structure by the epoxy groups present in the molecule. Examples of the weight-average molecular weight of the epoxy resin include preferably 50 to 2000, more preferably 100 to 1000, and even more preferably 200 to 800. Furthermore, 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.

[0144] Specific examples of epoxy resins include trimethylolpropane glycidyl ether derivatives, bisphenol A diglycidyl ether, modified bisphenol A diglycidyl ether, bisphenol F type glycidyl ether, novolac glycidyl ether, glycerin polyglycidyl ether, polyglycerin polyglycidyl ether, etc. The epoxy resin may be used as a single type or in combination of two or more types.

[0145] In the adhesive layer (5), the ratio of epoxy resin is preferably in the range of 0.1 to 50 mass% among the resin composition constituting the adhesive layer (5), and more preferably in the range of 0.5 to 40 mass%. This allows the adhesion between the barrier layer (3) and the adhesive layer (5) to be effectively increased.

[0146] As for the polyurethane, any known polyurethane can be used without special limitations. The adhesive layer (5) may be, for example, a cured product of a two-component curing polyurethane.

[0147] In the adhesive layer (5), the proportion of polyurethane is preferably in the range of 0.1 to 50 mass% among the resin composition constituting the adhesive layer (5), and more preferably in the range of 0.5 to 40 mass%. This allows for effective improvement in the adhesion between the barrier layer (3) and the adhesive layer (5) in an atmosphere where components that cause corrosion of the barrier layer, such as an electrolyte, are present.

[0148] And, when the adhesive layer (5) is a cured product of a resin composition comprising 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 component, 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.

[0149] The adhesive layer (5) may contain a modifier having a carbodiimide group.

[0150] 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, and about 5 μm or less. Also, the thickness of the adhesive layer (5) is preferably about 0.1 μm or more and about 0.5 μm or more. Additionally, the range of 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, and about 0.5 to 5 μm. More specifically, in the case of the adhesive layer (2) being an adhesive or a cured product of an acid-modified polyolefin and a curing agent, the thickness can preferably be 1 to 10 μm, more preferably 1 to 5 μm. Also, in the case of using the resin exemplified in the heat-fusible resin layer (4), the thickness can preferably be 2 to 50 μm, more preferably 10 to 40 μm. Furthermore, if the adhesive layer (5) is a cured product of a resin composition including the adhesive exemplified in the adhesive layer (2) or 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, etc. Also, if the resin exemplified in the heat-fusible resin layer (4) is used, it can be formed, for example, by extrusion molding of the heat-fusible resin layer (4) and the adhesive layer (5).

[0151] [Surface coating layer (6)]

[0152] The outer casing for a capacitor device of the present disclosure is intended to improve at least one of the following: design, electrolyte resistance, damage resistance, moldability, etc., and, if necessary, may have a surface coating layer (6) on the substrate layer (1) (on the opposite side from the barrier layer (3) of the substrate layer (1)).

[0153] The surface coating layer (6) is a layer located on the outermost layer side of the outer material for the energy storage device when the energy storage device is assembled using the outer material for the energy storage device.

[0154] The surface coating layer (6) can be formed from a resin such as polyvinylidene chloride, polyester, polyurethane, acrylic resin, epoxy resin, etc.

[0155] When the resin forming the surface coating layer (6) is a curable resin, the resin is preferably either a one-component curable type or a two-component curable type, but preferably a two-component curable type.

[0156] Examples of two-component curing resins include two-component curing polyurethane, two-component curing polyester, two-component curing epoxy resin, etc.

[0157] Among these, two-component curing polyurethane is preferred.

[0158] As for two-component curing polyurethanes, for example, there is a polyurethane comprising a first agent containing a polyol compound and a second agent containing an isocyanate compound. Preferably, an example of a two-component curing polyurethane can be given in which a polyol such as a polyester polyol, a polyether polyol, and an acrylic polyol is used as the first agent, and an aromatic or aliphatic polyisocyanate is used as the second agent. In addition, as for polyurethanes, there is a polyurethane compound in which a polyol compound and an isocyanate compound have been reacted beforehand, and a polyurethane containing an isocyanate compound. As for polyurethanes, for example, there is a polyurethane compound in which a polyol compound and an isocyanate compound have been reacted beforehand, and a polyurethane containing a polyol compound. As for polyurethanes, for example, there is a polyurethane in which a polyurethane compound in which a polyol compound and an isocyanate compound have been reacted beforehand is cured by reacting it with moisture such as air. As the polyol compound, it is preferable to use a polyester polyol having hydroxyl groups in the side chain in addition to the hydroxyl groups at the terminals of the repeating unit. As the second agent, examples of aliphatic, alicyclic, aromatic, or aromatic aliphatic isocyanate compounds may be used. Examples of isocyanate compounds include hexamethylene diisocyanate (HDI), xylylene diisocyanate (XDI), isophorone diisocyanate (IPDI), hydrogenated XDI (H6XDI), hydrogenated MDI (H12MDI), trilene diisocyanate (TDI), diphenylmethane diisocyanate (MDI), and naphthalene diisocyanate (NDI). In addition, examples of polyfunctional isocyanate modified compounds derived from one or more of these diisocyanates may be used. Furthermore, a polymer (e.g., a trimer) may be used as the polyisocyanate compound. Examples of such polymers include adducts, biurets, and nurates.In addition, an aliphatic isocyanate compound refers to an isocyanate having an aliphatic group and not an aromatic ring, a dicyclic isocyanate compound refers to an isocyanate having a dicyclic hydrocarbon group, and an aromatic isocyanate compound refers to an isocyanate having an aromatic ring. Excellent electrolyte resistance is imparted to the outer material for the capacitor device by the surface coating layer (6) being formed by polyurethane.

[0159] The surface coating layer (6) may include, if necessary, additives such as the aforementioned lubricant, anti-blocking agent, gloss remover, flame retardant, antioxidant, tackifier, anti-static agent, etc., on at least one of the surface and interior of the surface coating layer (6), depending on the functionality to be provided on the surface coating layer (6) or its surface. As for the additives, for example, there are fine particles with an average particle diameter of about 0.5 nm to 5 μm. The average particle diameter of the additive is the median diameter measured by a laser diffraction / scattering particle diameter distribution measuring device.

[0160] The additive may be either inorganic or organic. Furthermore, the shape of the additive is not particularly limited and may be, for example, spherical, fibrous, plate-like, irregular, or flake-like.

[0161] Specific examples of additives include talc, silica, graphite, kaolin, montmorillonite, mica, hydrotalcite, silica gel, zeolite, aluminum hydroxide, magnesium hydroxide, zinc oxide, magnesium oxide, aluminum oxide, neodymium oxide, antimony oxide, titanium oxide, cerium oxide, calcium sulfate, barium sulfate, calcium carbonate, calcium silicate, lithium carbonate, calcium benzoate, calcium oxalate, magnesium stearate, alumina, carbon black, carbon nanotubes, high melting point nylon, acrylate resin, cross-linked acrylic, cross-linked styrene, cross-linked polyethylene, benzoguanamine, gold, aluminum, copper, nickel, etc. The additive may be used as a single type or in combination of two or more types. Among these additives, silica, barium sulfate, and titanium oxide are preferably examples from the perspective of dispersion stability and cost. In addition, various surface treatments, such as insulation treatment and high dispersibility treatment, may be applied to the surface of the additive.

[0162] The method of forming the surface coating layer (6) is not particularly limited, and for example, there is a method of applying a resin that forms the surface coating layer (6). When an additive is mixed into the surface coating layer (6), the resin mixed with the additive can be applied.

[0163] As for the thickness of the surface coating layer (6), it is not particularly limited as long as it performs the above-mentioned function as a surface coating layer (6), and for example, about 0.5 to 10 μm, preferably about 1 to 5 μm can be given as an example.

[0164] 3. Method for manufacturing an outer casing for a capacitor device

[0165] Regarding the method for manufacturing an exterior material for a capacitor device, as long as a laminate can be obtained by laminating each layer of the exterior material for a capacitor device of the present disclosure, the method may be given as an example including a process of laminating at least a substrate layer (1), a barrier layer (3), and a heat-fusible resin layer (4) in this order. That is, the method for manufacturing an exterior material (10) for a capacitor device of the present disclosure is composed of a laminate having at least a substrate layer, a barrier layer, and a heat-fusible resin layer in this order, and the substrate layer includes a polyester film, and the polyester film has a work hardening index in the length direction and a work hardening index in the width direction of both 1.6 or more and 3.0 or less, and the difference between the work hardening index in the length direction and the width direction is 0.5 or less, the intrinsic viscosity is 0.66 or more and 0.95 or less, and the rigidity specific amount is 28% or more and 60% or less.

[0166] An example of a method for manufacturing an outer casing for a capacitor device according to the present disclosure is as follows. First, a laminate (hereinafter referred to as “Laminate (A)”) is formed in which a substrate layer (1), an adhesive layer (2), and a barrier layer (3) are laminated in order. Specifically, the formation of the laminate (A) can be carried out by a dry laminating method in which an adhesive used for forming an adhesive layer (2) is applied to a substrate layer (1) or, if necessary, a barrier layer (3) whose surface has been chemically treated, by a coating method such as gravure coating or roll coating, dried, and then the barrier layer (3) or the substrate layer (1) is laminated to cure the adhesive layer (2).

[0167] Next, a heat-fusible resin layer (4) is laminated onto the barrier layer (3) of the laminate (A). When directly laminating the heat-fusible resin layer (4) onto the barrier layer (3), the heat-fusible resin layer (4) can be laminated onto the barrier layer (3) of the laminate (A) by a method such as thermal laminating or extrusion laminating. In addition, when an adhesive layer (5) is installed between the barrier layer (3) and the heat-fusible resin layer (4), for example, 1) a method of laminating by extruding the adhesive layer (5) and the heat-fusible resin layer (4) onto the barrier layer (3) of the laminate (A) (co-extrusion laminating method, tandem laminating method), 2) a method of separately forming a laminate in which the adhesive layer (5) and the heat-fusible resin layer (4) are laminated, and laminating this onto the barrier layer (3) of the laminate (A) by a thermal laminating method, or a method of forming a laminate in which the adhesive layer (5) is laminated onto the barrier layer (3) of the laminate (A), and laminating this with the heat-fusible resin layer (4) by a thermal laminating method, 3) a melted adhesive layer (5) between the barrier layer (3) of the laminate (A) and the heat-fusible resin layer (4) that has been pre-made into a sheet shape There are methods for bonding a laminate (A) and a heat-fusible resin layer (4) through an adhesive layer (5) while injecting (sandwich laminating method), 4) a method of laminating by coating an adhesive solution to form an adhesive layer (5) on a barrier layer (3) of a laminate (A) and drying it, or further by baking, and laminating a heat-fusible resin layer (4) that has been pre-made into a sheet shape on the adhesive layer (5).

[0168] When installing the surface coating layer (6), the surface coating layer (6) is laminated on the surface opposite to the barrier layer (3) of the substrate layer (1). The surface coating layer (6) can be formed, for example, by applying the resin described above, which forms the surface coating layer (6), to the surface of the substrate layer (1). Furthermore, the order of the process of laminating the barrier layer (3) on the surface of the substrate layer (1) and the process of laminating the surface coating layer (6) on the surface of the substrate layer (1) is not particularly limited. For example, after forming the surface coating layer (6) on the surface of the substrate layer (1), the barrier layer (3) may be formed on the surface opposite to the surface coating layer (6) of the substrate layer (1).

[0169] As described above, a laminate is formed having a surface coating layer (6) installed as needed, a substrate layer (1), an adhesive layer (2) installed as needed, a barrier layer (3), an adhesive layer (5) installed as needed, and a heat-fusible resin layer (4) in this order, but in order to strengthen the adhesion of the adhesive layer (2) and the adhesive layer (5) installed as needed, further heat treatment may be provided.

[0170] In the case of an outer casing for a storage device, the processing suitability of each layer constituting the laminate may be improved by performing surface activation treatments such as corona treatment, blast treatment, oxidation treatment, or ozone treatment as needed. For example, by performing corona treatment on the surface opposite to the barrier layer (3) of the substrate layer (1), the printing suitability of ink to the surface of the substrate layer (1) can be improved.

[0171] 4. Uses of exterior materials for energy storage devices

[0172] The outer casing for a capacitor device of the present disclosure is used in a packaging body for sealing and accommodating capacitor device elements such as an anode, a cathode, and an electrolyte. That is, a capacitor device element having at least an anode, a cathode, and an electrolyte can be accommodated in a packaging body formed by the outer casing for a capacitor device of the present disclosure to form a capacitor device.

[0173] Specifically, a capacitor device having at least a positive electrode, a negative electrode, and an electrolyte is covered with an outer casing for a capacitor device according to the present disclosure, with metal terminals connected to each of the positive electrode and the negative electrode protruding outward, so that a flange portion (an area where heat-fusible resin layers come into contact with each other) is formed on the peripheral edge of the capacitor device, and the heat-fusible resin layers of the flange portion are heat-sealed to seal them, thereby providing a capacitor device using an outer casing for a capacitor device. Furthermore, when the capacitor device is housed in a packaging body formed by the outer casing for a capacitor device according to the present disclosure, the packaging body is formed such that the heat-fusible resin portion of the outer casing for a capacitor device according to the present disclosure becomes the inner side (the surface in contact with the capacitor device). Two heat-fusible resin layers of exterior materials for capacitor devices may be overlapped facing each other, and the surrounding edges of the overlapped exterior materials for capacitor devices may be heat-fused to form a packaging body. Alternatively, as shown in the example in FIG. 5, one exterior material for capacitor devices may be folded and overlapped, and the surrounding edges may be heat-fused to form a packaging body. In the case of folding and overlapping, as shown in the example in FIG. 5, the sides other than the folded side may be heat-fused to form a packaging body by three-way sealing, or the sides may be folded to form a flange portion and sealed by four-way sealing. Additionally, a concave portion for accommodating capacitor device elements may be formed in the exterior material for capacitor devices by deep drawing molding or stretch molding. As shown in the example in FIG. 5, a concave portion may be formed in one exterior material for capacitor devices and not formed in the other exterior material for capacitor devices, or a concave portion may be formed in the other exterior material for capacitor devices.

[0174] The casing material for a storage device disclosed in the present disclosure can preferably be used in a storage device such as a battery (including condensers, capacitors, etc.). Furthermore, the casing material for a storage device disclosed in the present disclosure may be used in either a primary battery or a secondary battery, but is preferably used in a secondary battery. The types of secondary batteries to which the casing material for a storage device disclosed in the present disclosure is applied are not particularly limited and include, for example, lithium-ion batteries, lithium-ion polymer batteries, all-solid-state batteries, lead-acid batteries, nickel-hydrogen batteries, nickel-cadmium batteries, nickel-iron batteries, nickel-zinc batteries, silver oxide-zinc batteries, metal dry batteries, polyvalent cation batteries, condensers, capacitors, etc. Among these secondary batteries, lithium-ion batteries and lithium-ion polymer batteries can be cited as examples of preferred applications for the casing material for a storage device disclosed in the present disclosure.

[0175] Examples

[0176] Examples and comparative examples are presented below, and the present disclosure is described in detail. However, the present disclosure is not limited to the examples.

[0177] [Examples 1–13 and Comparative Examples 1–2]

[0178] <Manufacturing and Evaluation of Polyester Films>

[0179] The polyester film was manufactured and evaluated using the following method.

[0180] (1) Composition of polyester

[0181] Polyester resin and film are dissolved in hexafluoroisopropanol (HFIP), and 1 H-NMR and 13 The content of each monomer residue or byproduct diethylene glycol was quantified using C-NMR.

[0182] (2) Film thickness, layer thickness

[0183] When measuring the total thickness of the film, a dial gauge was used, the film was cut into 200mm × 300mm sections, and the thickness of each sample was measured at five random locations and averaged. In addition, the thickness of each layer of the film and exterior material was determined by embedding the sample in epoxy resin, cutting the cross-section of the film with a microtome, and observing the cross-section at a magnification of 5000x using a transmission electron microscope (TEMH7100 manufactured by Hitachi, Ltd.).

[0184] (3) Length and width directions of the polyester film

[0185] In the present disclosure, the film is tested for breaking strength in any direction (0°), and in directions 15°, 30°, 45°, 60°, 75°, 90°, 105°, 120°, 135°, 150°, and 165° from the above direction. The direction with the highest breaking strength is set as the width direction, and the direction perpendicular to the width direction is set as the length direction. The breaking strength can be obtained by the method shown in “(6) Breaking Elongation”. In “(6) Elongation at Break”, a rectangular sample with a long side of 150 mm × a short side of 10 mm is cut and measured, but the long side is cut and measured so that it aligns with any one direction (0°) of the film mentioned above, and 12 directions from the above direction: 15°, 30°, 45°, 60°, 75°, 90°, 105°, 120°, 135°, 150°, and 165°.

[0186] (4) Intrinsic viscosity

[0187] The solution viscosity of the polyester film in orthochlorophenol was measured using an Oswald viscometer at 25°C, and the value was calculated from the solution viscosity. The unit of intrinsic viscosity is expressed as [dl / g]. The value of n was set to 3, and the average value was adopted.

[0188] (5) Planar orientation coefficient fn of polyester film

[0189] Using an Abbe refractive index meter, a layer (hereinafter referred to as the measurement layer) to be measured for plane orientation coefficient was placed in contact with a glass surface, and then, using sodium D rays as a light source, the refractive indices (Nx, Ny, Nz) in the a direction, b direction, and thickness direction were measured, and the plane orientation coefficient fn of the measurement layer was calculated by the following formula.

[0190] · Planar orientation coefficient fn = (Nx + Ny) / 2 - Nz

[0191] (6) Breaking the Shindo

[0192] The film was cut into a rectangular shape measuring 150 mm in length × 10 mm in width in the length and width directions to serve as a sample. Under conditions of 25°C and 63% Rh, a tensile test was performed on the film in the length and width directions using a tensile testing machine (Densilon AMF / RTA-100, an automatic film tensile strength measuring device manufactured by Orientech Co., Ltd.) with a crosshead speed of 300 mm / min, a width of 10 mm, and a sample length of 50 mm. The elongation at break was read and recorded as the elongation at break. The measurement was performed five times, and the average was used.

[0193] (7) Crystallinity

[0194] In accordance with JISK 7122 (1999), the differential scanning calorimeter robot DSC-RDC220 manufactured by Seiko Electronics Co., Ltd. was used, and the "disk session" SSC / 5200 was used for data analysis. A 5 mg film sample was heated from room temperature to 300°C at a heating rate of 20°C / min on an aluminum plate and maintained at 300°C for 5 minutes. At this time, the heat of the endothermic peak ΔHm, the heat of cold crystallization ΔHc, and the heat of melting of fully crystalline PET ΔHm0 (140.1 J / g) obtained by measurement were calculated using the following formula.

[0195] Degree of crystallinity (%) = (ΔHm - ΔHc) / ΔHm0 x 100

[0196] (8) Non-determined rigidity

[0197] The specific rigidity was calculated using the following formula from the movable specificity and crystallinity obtained by measurement.

[0198] Rigidity quantity (%) = 100 - (operation quantity + crystallinity).

[0199] Theoretical value of specific heat difference of perfectly amorphous polyethylene terephthalate = 0.4052 J / (g℃)

[0200] In addition, the present disclosure refers to the theoretical value of the specific heat difference of a completely non-perishable polyethylene terephthalate.

[0201] In addition, the specific operating quantity was measured as follows. Using a temperature-modulated DSC manufactured by TA Instruments, 5 mg of the sample was measured under a nitrogen atmosphere from 0°C to 150°C at a heating rate of 2°C / min, a temperature modulation amplitude of ±1°C, and a temperature modulation period of 60 seconds. The difference in specific heat at the glass transition temperature obtained from the measurement was determined and calculated using the following formula.

[0202] Operating Specific Quantity (%) = (Specific Heat Difference) / (Theoretical Value of Specific Heat Difference of Perfectly Unspecified Polyester) × 100

[0203] Theoretical value of specific heat difference of polyethylene terephthalate (perfectly amorphous) = 0.4052 J / (g℃)

[0204] In addition, regarding the polyethylene terephthalate unit being 70 mol% or more in the present disclosure, the theoretical value of the specific heat difference of a completely non-perishable polyethylene terephthalate was referenced.

[0205] (9) Glass transition temperature (Tg), melting point (melting endothermic peak temperature (Tm))

[0206] In accordance with JISK 7122 (1999), using a differential scanning calorimeter (EXSTARDSC6220 manufactured by Seiko Instruments), 3 mg of resin was heated from 30°C to 300°C at a rate of 20°C / min in a nitrogen atmosphere. Next, after maintaining the temperature at 300°C for 5 minutes, it was lowered to 30°C at a rate of 40°C / min. Additionally, after maintaining the temperature at 30°C for 5 minutes, it was heated from 30°C to 300°C at a rate of 20°C / min. The glass transition temperature obtained during this heating process was calculated by the following equation (i).

[0207] Glass transition temperature = (out-of-bounds glass transition onset temperature + out-of-bounds glass transition end temperature) / 2… (i)

[0208] Here, the extra-extra-glass transition initiation temperature is defined as the temperature at the intersection of the straight line extending the baseline on the low-temperature side to the high-temperature side and the tangent line drawn at the point where the gradient of the curve of the step-shaped change portion of the glass transition is maximized. The extra-extra-glass transition termination temperature is defined as the temperature at the intersection of the straight line extending the baseline on the high-temperature side to the low-temperature side and the tangent line drawn at the point where the gradient of the curve of the step-shaped change portion of the glass transition is maximized. In addition, the peak top of the endothermic peak due to the crystal melting of the resin was defined as the melting point (melting endothermic peak temperature (Tm)).

[0209] (10) Work hardening index

[0210] The film was cut into rectangular pieces measuring 150 mm in length × 10 mm in width along the length and width directions to be used as samples. Under conditions of 25°C and 63% Rh, a tensile test was performed on the film in the length and width directions using a tensile testing machine ("Densilon AMF / RTA-100," an automatic film tensile strength measuring device manufactured by Orientech Co., Ltd.), with a crosshead speed of 300 mm / min, a width of 10 mm, and a sample length (distance between gauge points) of 50 mm, and the initial length was L 0 (mm), length at 5% elongation L 1 (mm), nominal stress at 5% elongation P 1(MPa), length at 60% elongation L 2 (mm), nominal stress at 60% elongation P 2 When set to (MPa), the true strain at 5% elongation is the value obtained from Equation (1), the true strain at 60% elongation is the value obtained from Equation (2), the true stress at 5% elongation is the value obtained from Equation (3), and the true stress at 60% elongation is the value obtained from Equation (4). From the values ​​obtained from (1) to (4), the slope obtained from the equation formed when the X-axis represents true strain and the Y-axis represents true stress was used as the work hardening index. The average value obtained when measuring this five times each in the length direction and the width direction was adopted.

[0211] True deformation at 5% elongation = L n (L 1 / L 0 )… (1)

[0212] True deformation at 60% elongation = L n (L 2 / L 1 )… (2)

[0213] True stress at 5% elongation = L n (P 1 (1+L n (L 1 / L 0 )))… (3)

[0214] True stress at 60% elongation = L n (P 2 (1+L n (L 2 / L 1 )))… (4)

[0215] ※L n : Natural logarithm

[0216] (11) Thermal shrinkage rate of polyester film in the length and width directions at 150°C

[0217] A film was cut into a rectangular shape measuring 150 mm in length × 10 mm in width along the length and width directions to serve as a sample. Marking lines were drawn on the sample at intervals of 100 mm, and a 3 g weight was attached to it. The sample was then placed in a hot air oven heated to 150°C for 30 minutes to perform heat treatment. The distance between the marking lines after heat treatment was measured, and the thermal shrinkage rate was calculated from the change in the distance between the marking lines before and after heating. Measurements were performed on 5 samples in the length and width directions, and the average value was used for evaluation.

[0218] (12) Dynamic friction coefficient of polyester film

[0219] Using a slip tester manufactured by Toyo Seiki Co., Ltd., the stable region of the resistance value after the initial operation was measured when the two sides of the film were overlapped and rubbed in accordance with JIS-K7125 (1999), and this was defined as the coefficient of kinetic friction μd. The sample was made into a rectangle with a width of 80 mm and a length of 200 mm, and 3 sets (6 sheets) were cut from the roll along the length of the rectangle. Three measurements were taken, and the average value was calculated.

[0220] (13) Wrinkles during extrusion lamination

[0221] 60,000mm cut from each exterior material obtained by the method described in <Manufacture of Exterior Material for Capacitive Device> below 2 Regarding the range, the appearance was visually inspected, and a judgment was made as follows.

[0222] ○: No wrinkles were observed throughout the film.

[0223] △: Wrinkles of less than 5 mm were observed.

[0224] ×: Wrinkles of 5 mm or more were observed.

[0225] (Manufacture of polyester film)

[0226] The resin constituting the polyester film provided for film formation was prepared by mixing the main raw material, auxiliary raw material, and particle master for each example and each comparative example in the types and ratios listed in Table 1. In addition, the main raw material, auxiliary raw material, and particle master used in each example and each comparative example were prepared as follows.

[0227] · Polyester A

[0228] Polyethylene terephthalate resin having 100 mol% terephthalic acid as a dicarboxylic acid component and 100 mol% ethylene glycol as a glycol component (intrinsic viscosity 0.72).

[0229] · Polyester B

[0230] Polyethylene terephthalate resin having 100 mol% terephthalic acid as a dicarboxylic acid component and 100 mol% ethylene glycol as a glycol component (intrinsic viscosity 0.82).

[0231] · Polyester C

[0232] Polyethylene terephthalate resin having 100 mol% terephthalic acid as a dicarboxylic acid component and 100 mol% ethylene glycol as a glycol component (intrinsic viscosity 0.92).

[0233] · Polyester D

[0234] Polybutylene terephthalate resin having 100 mol% terephthalic acid as a dicarboxylic acid component, 1-4 as a glycol component, and 100 mol% butanediol component (intrinsic viscosity 1.2).

[0235] · Polyester E

[0236] Polyethylene terephthalate resin having 100 mol% terephthalic acid as a dicarboxylic acid component and 100 mol% ethylene glycol as a glycol component (intrinsic viscosity 0.65).

[0237] · Particle Master A

[0238] Polyethylene terephthalate particle master containing aggregated silica particles with an average particle diameter of 1.2 μm in polyester A at a particle concentration of 2 mass%.

[0239] (Topical Agent A)

[0240] · Acrylic resin comprising a copolymer composition of methyl methacrylate / ethyl acrylate / acrylic acid / N-methylolacrylamide = 63 / 35 / 1 / 1 mass%: 3.00 mass%

[0241] · Melamine crosslinking agent: 0.75 mass%

[0242] · Colloidal silica particles (average particle size: 80 nm): 0.15 mass%

[0243] ·Hexanol: 0.26 mass%

[0244] · Butyl cellosolve: 0.18 mass%

[0245] · Water: 95.66 mass%

[0246] An extruder was used, and the polyester types and particle masters listed in Table 1 were each dried in a vacuum dryer at 180°C for 4 hours to sufficiently remove moisture. Then, the main raw materials, auxiliary raw materials, and particle masters were fed into the extruder as described in Table 1 and melted at 280°C. Subsequently, the resin extruded from the extruder and the resin discharged from the nozzle were cooled and solidified on a cast drum cooled to 25°C to obtain an unoriented sheet. At this time, the distance between the lip of the T-die and the cooling drum was set to 35 mm, and electrostatic charge was applied at a voltage of 14 kV using a wire-type electrode with a diameter of 0.1 mm to bring the sheet into close contact with the cooling drum. In addition, the passing speed of the unoriented sheet through the cooling drum was set to 25 m / min, and the contact length of the unoriented sheet with the cooling drum was set to 2.5 m.

[0247] Next, the above-mentioned unoriented sheet was preheated with a group of rolls heated to the temperature listed in Table 2, then stretched in the longitudinal direction (vertical direction) at the magnification shown in Table 2 using a heating roll controlled to the temperature listed in Table 2, and cooled with a group of rolls at a temperature of 25°C to obtain a uniaxially stretched film. Corona discharge treatment was performed on this uniaxially stretched film in air, and coating agent A was mixed as an anchor coating layer on the treated surface while ultrasonically dispersing it, and surface treatment was performed by uniformly applying it to the surface bonded with the #4 metalling bar cast. Subsequently, while gripping both ends of the uniaxially stretched film with clips, the inside of the denta was guided to a preheating zone controlled to the temperature listed in Table 2, and was then continuously stretched in a direction perpendicular to the longitudinal direction (width direction) at the magnification shown in Table 2 in a heating zone maintained at the temperature listed in Table 2. Next, heat treatment was performed for 20 seconds at the heat treatment temperature shown in Table 2 in the heat treatment zone within the denter, and relaxation treatment was performed at the relaxation temperature shown in Table 2 at the relaxation rate shown in Table 2. Then, the film was uniformly slow-cooled to obtain a polyester film with the thickness shown in Table 1. The characteristics of the polyester film are as shown in Table 3.

[0248] Manufacture of exterior materials for capacitor devices

[0249] In Examples 1 to 12 and Comparative Examples 1 to 2, a polyester film obtained by the above-described method was used as a substrate layer, and an outer casing for a capacitor device was manufactured in the following order. Each polyester film (PET, thickness 25 μm) was prepared as the substrate layer, and an aluminum foil (JIS H4160:1994 A8021H-O, thickness 40 μm) was prepared as the barrier layer with a corrosion-resistant film formed on both sides. Next, a laminate of a substrate layer (thickness 25 μm) / adhesive layer (thickness after curing 3 μm) / barrier layer (thickness 40 μm) was produced by using a two-component curing urethane adhesive (polyol compound and aromatic isocyanate compound), laminating the substrate layer and the barrier layer by a dry laminating method, and performing an aging treatment. In addition, in Example 13, a laminated film (PET / ONy) obtained by the above-described method, in which a resin film (polyethylene terephthalate film thickness is 12 μm) and a stretched nylon film (thickness 15 μm) are laminated with a two-component curing urethane adhesive (thickness after curing of a polyol compound and an aromatic isocyanate compound is 3 μm), was used as a substrate layer, and an outer casing for a capacitor device was manufactured in the following steps. A laminated film (PET / ONy) as a substrate layer and an aluminum foil (JIS H4160:1994 A8021H-O, thickness 40 μm) as a barrier layer having a corrosion-resistant film formed on both sides were prepared. Next, using a two-component curing urethane adhesive (polyol compound and aromatic isocyanate compound), the ONy side of the substrate layer and the barrier layer were laminated by a dry laminating method, and an aging treatment was performed to produce a laminate of a substrate layer (thickness 30 μm) / adhesive layer (thickness after curing 3 μm) / barrier layer (thickness 40 μm).

[0250] Next, maleic anhydride-modified polypropylene (PPa, thickness 40 μm) as an adhesive layer and polypropylene (PP, thickness 40 μm) as a heat-fusible resin layer were co-extruded onto the barrier layer of the obtained laminate, thereby laminating the adhesive layer / heat-fusible resin layer onto the barrier layer. Next, the obtained laminate was aged and heated to obtain an outer casing for a capacitor device in which a polyester film / adhesive layer / barrier layer / adhesive layer / heat-fusible resin layer were laminated in this order.

[0251] And, erucic acid amide was applied as a lubricant to the outer surface of the substrate layer of each capacitor device.

[0252] <Evaluation of Plasticity>

[0253] An outer casing for a capacitor device was cut into a rectangle with a length (MD (Machine Direction)) of 90 mm × a width (TD (Transverse Direction)) of 150 mm and used as a test sample. This sample was formed using a rectangular forming die having a diameter of 31.6 mm (MD direction) × 54.5 mm (TD) (female die, surface, as specified in Table 2 of Annex 1 (Reference) of Comparative Surface Roughness Standards for JIS B 0659-1:2002, with a maximum height roughness (Rz arc) of 3.2 μm, corner R 2.0 mm, ridge R 1.0 mm) and a corresponding forming die (male die, surface, as specified in Table 2 of Annex 1 (Reference) of Comparative Surface Roughness Standards for JIS B 0659-1:2002, with a maximum height roughness (Rz arc) of 1.6 μm, corner R 2.0 mm, ridge R 1.0 mm), with a pressing pressure (surface pressure) of 0.25 MPa, starting from a forming depth of 0.5 mm and decreasing the forming depth in increments of 0.5 mm The process was modified, and cold forming (inlet 1-stage forming) was performed on 10 samples each. At this time, the test samples were mounted on the female mold and formed so that the heat-fusible resin layer side was positioned on the male mold side. Additionally, the clearance between the male and female molds was set to 0.3 mm. Forming was performed in a 25°C environment. After cold forming, the samples were illuminated with a penlight in a dark room, and the presence of pinholes or cracks in the aluminum alloy foil was checked by light transmission. The deepest forming depth at which no pinholes or cracks occurred in any of the 10 samples was set to A mm, and the number of samples with pinholes, etc. at the shallowest forming depth at which pinholes, etc. occurred in the aluminum alloy foil was set to B. The value calculated by the following formula was rounded to the second decimal place and set as the limit forming depth for the outer casing material for the capacitor device. For each, the depth criteria were determined in four stages as follows. The results are shown in Table 3.

[0254] Limit forming depth = Amm + (0.5mm / 10 pieces) × (10 pieces - B pieces)

[0255] (Criteria for evaluating plasticity)

[0256] S: Limit forming depth is 6.5mm or more

[0257] A: Limit forming depth is 6.0mm or more and less than 6.5mm

[0258] B: Limit forming depth is 5.0mm or more and less than 6.0mm

[0259] C: Limit forming depth is 4.5mm or more and less than 5.0mm

[0260] D: Limit forming depth is less than 4.5mm

[0261] [Table 1]

[0262]

[0263] [Table 2]

[0264]

[0265] [Table 3]

[0266]

[0267] As described above, the present disclosure provides an invention of the following type.

[0268] Claim 1. At least, the laminate comprises a substrate layer, a barrier layer, and a heat-fusible resin layer in this order, and

[0269] The above substrate layer comprises a polyester film, and

[0270] The above polyester film is an outer material for a capacitor device, wherein the work hardening index in both the length direction and the width direction is 1.6 or higher and 3.0 or lower, the difference between the work hardening index in the length direction and the width direction is 0.5 or lower, the intrinsic viscosity is 0.66 or higher and 0.95 or lower, and the rigidity specific amount is 28% or higher and 60% or lower.

[0271] Claim 2. An outer casing for a capacitor device as described in Claim 1, wherein the thickness of the polyester film is 5㎛ or more and 40㎛ or less.

[0272] Claim 3. An outer casing for a capacitor device as described in Claim 1 or 2, wherein the melting point of the polyester film is 235°C or higher.

[0273] Claim 4. An outer casing for a capacitor device as described in any one of Claims 1 to 3, wherein the degree of crystallization of the polyester film is 15% or more and 40% or less.

[0274] Claim 5. An outer casing for a capacitor device as described in any one of Claims 1 to 4, wherein the elongation at break in at least one of the longitudinal and width directions of the polyester film is 100% or more.

[0275] Claim 6. A storage device having at least a positive electrode, a negative electrode, and an electrolyte, wherein the storage device element is housed in a packaging formed by an outer casing for a storage device as described in any one of claims 1 to 5.

[0276] Claim 7. At least, the process includes stacking a substrate layer, a barrier layer, and a heat-fusible resin layer in this order to obtain a laminate, and

[0277] The above substrate layer comprises a polyester film, and

[0278] A method for manufacturing an outer casing for a capacitor device, wherein the polyester film has a work hardening index in both the length direction and the width direction of 1.6 or higher and 3.0 or lower, a difference between the work hardening index in the length direction and the width direction of 0.5 or lower, an intrinsic viscosity of 0.66 or higher and 0.95 or lower, and a rigidity specific amount of 28% or higher and 60% or lower. Explanation of the symbols

[0279] 1: Base layer 2: Adhesive layer 3: Barrier layer 4: Heat-fusible resin layer 5: Adhesive layer 6: Surface coating layer 10: Exterior materials for capacitor devices

Claims

Claim 1 An outer casing for a storage device, comprising a laminate having at least a substrate layer, a barrier layer, and a heat-fusible resin layer in this order, wherein the substrate layer comprises a polyester film, and the polyester film has a work hardening index in both the length direction and the width direction of 1.6 or higher and 3.0 or lower, and the difference between the work hardening index in the length direction and the width direction is 0.5 or lower, the intrinsic viscosity is 0.66 or higher and 0.95 or lower, and the rigidity non-crystalline content is 28% or higher and 60% or lower. Claim 2 An outer casing for a storage device according to claim 1, wherein the thickness of the polyester film is 5㎛ or more and 40㎛ or less. Claim 3 An outer material for a storage device according to claim 1 or 2, wherein the melting point of the polyester film is 235°C or higher. Claim 4 An outer material for a storage device according to claim 1 or 2, wherein the degree of crystallization of the polyester film is 15% or more and 40% or less. Claim 5 An outer material for a capacitor device according to claim 1 or 2, wherein the elongation at break in at least one of the length direction and the width direction of the polyester film is 100% or more. Claim 6 A capacitor device having at least a positive electrode, a negative electrode, and an electrolyte, wherein the capacitor device element is contained within a package formed by an outer casing for a capacitor device as described in claim 1 or 2. Claim 7 A method for manufacturing an outer casing for a capacitor device, comprising a process of obtaining a laminate by laminating at least a substrate layer, a barrier layer, and a heat-fusible resin layer in this order, wherein the substrate layer comprises a polyester film, and the polyester film has a work hardening index in both the length direction and the width direction of 1.6 or higher and 3.0 or lower, and the difference between the work hardening index in the length direction and the width direction is 0.5 or lower, the intrinsic viscosity is 0.66 or higher and 0.95 or lower, and the rigidity specific amount is 28% or higher and 60% or lower.

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