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

Abstract

To provide an exterior material for a power storage device that is composed of a laminate having at least a base material layer, a barrier layer, and a heat-fusible resin layer in this order, which effectively suppresses collapse when the heat-fusible resin layer is heat-melted.SOLUTION: An exterior material for a power storage device is composed of a laminate having at least a base material layer, a barrier layer, and a heat-fusible resin layer in this order, wherein the heat-fusible resin layer is composed of a single layer or a multilayer, and in the heat-fusible resin layer, a first heat-fusible resin layer constituting the surface of the laminate has a logarithmic decrement ΔE at 140°C in rigid body pendulum measurement is 0.20 or less.SELECTED DRAWING: Figure 2

Description

[Technical Field]

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

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

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

[0004] Therefore, in recent years, a film-like laminate in which a base layer, a barrier layer, and a heat-sealable resin layer are laminated in this order has been proposed as an exterior material for an electricity storage device that can be easily processed into a variety of shapes and can be made thinner and lighter (see, for example, Patent Document 1).

[0005] In such an electrical storage device packaging material, a recess is generally formed by cold forming, and electrical storage device elements such as electrodes and electrolyte are placed in the space formed by the recess, and a heat-sealable resin layer is heat-sealed to obtain an electrical storage device in which the electrical storage device elements are housed inside the electrical storage device packaging material. [Prior art documents] [Patent documents]

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

[0007] When sealing an electricity storage device element, a heat-sealable resin layer is heat-sealed by applying high temperature and high pressure to the electricity storage device exterior material using a metal plate, etc. However, through investigations by the inventors of the present disclosure, they found that applying high temperature and high pressure to the electricity storage device exterior material crushes the heat-sealable resin layer located on the surface, thereby reducing the insulating properties of the electricity storage device exterior material.

[0008] Under these circumstances, the main object of the present invention is to provide an exterior packaging material for an electricity storage device that is composed of a laminate having at least a base material layer, a barrier layer, and a heat-sealable resin layer in this order, and that is effectively suppressed from collapsing when the heat-sealable resin layer is heat-sealed. [Means for solving the problem]

[0009] The inventors of the present disclosure conducted extensive research to solve the above-mentioned problems, and as a result, found that an exterior packaging material for an electricity storage device, which is composed of a laminate including at least a base material layer, a barrier layer, and a heat-sealable resin layer in this order, wherein the heat-sealable resin layer is composed of a single layer or multiple layers, and wherein a first heat-sealable resin layer constituting the surface of the laminate among the heat-sealable resin layers has a logarithmic decrement ΔE at 140°C in rigid pendulum measurement of 0.20 or less, can effectively suppress collapse when the heat-sealable resin layer is heat-sealed.

[0010] The present disclosure has been completed based on these findings and further investigations. That is, the present disclosure provides the inventions of the following aspects. The laminate is composed of at least a base layer, a barrier layer, and a heat-sealable resin layer in this order, the heat-fusible resin layer is composed of a single layer or multiple layers, An exterior material for an electricity storage device, wherein a first heat-sealable resin layer constituting the surface of the laminate among the heat-sealable resin layers has a logarithmic decrement ΔE of 0.20 or less at 140°C in a rigid pendulum measurement. [Effects of the Invention]

[0011] According to the present disclosure, it is possible to provide a packaging material for an electricity storage device that is composed of a laminate including at least a base material layer, a barrier layer, and a heat-sealable resin layer in this order, in which crushing when the heat-sealable resin layer is heat-sealed is effectively suppressed. By suppressing crushing, for example, improved insulation properties can be expected. Furthermore, according to the present disclosure, it is also possible to provide a method for manufacturing a packaging material for an electricity storage device, and an electricity storage device. [Brief explanation of the drawings]

[0012] [Figure 1] 1 is a schematic diagram showing an example of a cross-sectional structure of an exterior packaging material for an electricity storage device according to the present disclosure. [Figure 2] 1 is a schematic diagram showing an example of a cross-sectional structure of an exterior packaging material for an electricity storage device according to the present disclosure. [Figure 3] 1 is a schematic diagram showing an example of a cross-sectional structure of an exterior packaging material for an electricity storage device according to the present disclosure. [Figure 4] 1 is a schematic diagram showing an example of a cross-sectional structure of an exterior packaging material for an electricity storage device according to the present disclosure. [Figure 5] 1 is a schematic diagram showing an example of a cross-sectional structure of an exterior packaging material for an electricity storage device according to the present disclosure. [Figure 6] FIG. 1 is a schematic diagram for explaining a method for measuring a logarithmic decrement ΔE by rigid pendulum measurement. [Figure 7] 1 is a photomicrograph (taken at a magnification of 20 times) of a cross section of a heat-sealed portion between heat-sealable resin layers of an exterior packaging material for an electricity storage device obtained in Example 1. [Figure 8] 1 is a photomicrograph (taken at 20x magnification) of a cross section of a heat-sealed portion between heat-sealable resin layers of an exterior packaging material for an electricity storage device obtained in Example 2. [Figure 9]1 is a photomicrograph (taken at a magnification of 20 times) of a cross section of a heat-sealed portion between heat-sealable resin layers of an exterior packaging material for an electricity storage device obtained in Comparative Example 1. [Figure 10] 1 is a photomicrograph (taken at 20x magnification) of a cross section of a heat-sealed portion between heat-sealable resin layers of an exterior packaging material for an electricity storage device obtained in Comparative Example 2. [Figure 11] 10 is a schematic diagram for explaining a protrusion formed inside a heat-sealed portion of a heat-sealable resin layer. FIG. DETAILED DESCRIPTION OF THE INVENTION

[0013] The packaging material for an electricity storage device of the present disclosure is composed of a laminate having at least a base layer, a barrier layer, and a heat-sealable resin layer in this order, the heat-sealable resin layer being composed of a single layer or multiple layers, and the first heat-sealable resin layer constituting the surface of the laminate among the heat-sealable resin layers is characterized in that the logarithmic decrement ΔE at 140°C in rigid pendulum measurement is 0.20 or less. By having this configuration, the packaging material for an electricity storage device of the present disclosure is effectively suppressed from collapsing when the heat-sealable resin layer is heat-sealed.

[0014] The packaging material for an electricity storage device of the present disclosure will be described in detail below. In this specification, a numerical range indicated by "to" means "not less than" or "not more than." For example, the expression "2 to 15 mm" means 2 mm or more and 15 mm or less.

[0015] 1.Layer structure of exterior materials for energy storage devices As shown in Figs. 1 to 5, for example, an electrical storage device packaging material 10 according to the present disclosure is composed of a laminate including at least a base material layer 1, a barrier layer 3, and a heat-sealable resin layer 4 in this order. In the electrical storage device packaging material 10, the base material layer 1 is the outermost layer, and the heat-sealable resin layer 4 is the inner layer. In the electrical storage device packaging material 10 according to the present disclosure, the heat-sealable resin layer 4 is composed of a single layer or multiple layers, and of the heat-sealable resin layer 4, a first heat-sealable resin layer 41 forms the surface of the laminate. Figs. 1 and 2 illustrate a laminate configuration in which the heat-sealable resin layer 4 is composed of a single layer of the first heat-sealable resin layer 41, and the first heat-sealable resin layer 41 forms the surface of the laminate. 3 to 5 show a laminated structure in which the heat-sealable resin layer 4 is made up of multiple layers (two layers) of a first heat-sealable resin layer 41 and a second heat-sealable resin layer 42, with the first heat-sealable resin layer 41 forming the surface of the laminate. As will be described later, the heat-sealable resin layer 4 may further include, in addition to the first heat-sealable resin layer 41 and the second heat-sealable resin layer 42, other heat-sealable resin layers such as a third heat-sealable resin layer and a fourth heat-sealable resin layer on the barrier layer 3 side of the second heat-sealable resin layer 42.

[0016] When assembling an electricity storage device using the exterior packaging material 10 for an electricity storage device and an electricity storage device element, the first heat-sealable resin layers 41 of the exterior packaging material 10 for an electricity storage device are placed facing each other, and the electricity storage device element is housed in a space formed by heat-sealing the peripheral portions.

[0017] As shown in Figures 2 to 5, for example, the packaging material 10 for an electricity storage device may have an adhesive layer 2 between the base material layer 1 and the barrier layer 3, if necessary, for the purpose of increasing the adhesion between these layers. Furthermore, as shown in Figures 2, 4, and 5, for example, the packaging material 10 for an electricity storage device may have an adhesive layer 5 between the barrier layer 3 and the heat-sealable resin layer 4, if necessary, for the purpose of increasing the adhesion between these layers. Furthermore, as shown in Figure 5, a surface coating layer 6 or the like may be provided on the outer side of the base material layer 1 (the side opposite to the heat-sealable resin layer 4 side), if necessary.

[0018] The thickness of the laminate constituting the electrical storage device packaging material 10 is not particularly limited, but from the viewpoint of cost reduction, improving energy density, etc., it is preferably about 180 μm or less, about 155 μm or less, and from the viewpoint of maintaining the function of the electrical storage device packaging material to protect the electrical storage device elements, it is preferably about 35 μm or more, about 45 μm or more, about 60 μm or more, and preferred ranges include, for example, about 35 to 180 μm, about 35 to 155 μm, about 45 to 180 μm, about 45 to 155 μm, about 60 to 180 μm, and about 60 to 155 μm.

[0019] 2. Each layer that forms the exterior material for the energy storage device [Base material layer 1] In the present disclosure, the substrate layer 1 is a layer provided for the purpose of allowing the packaging material for an electricity storage device to function as a substrate. The substrate layer 1 is located on the outer layer side of the packaging material for an electricity storage device.

[0020] There are no particular limitations on the material forming the base layer 1, as long as it functions as a base, i.e., has at least insulating properties. The base layer 1 can be formed using, for example, a resin, which may contain additives described below.

[0021] When the base layer 1 is formed of a resin, the base layer 1 may be, for example, a resin film formed of a resin, or may be formed by applying a resin. The resin film may be an unstretched film or a stretched film. Examples of stretched films include uniaxially stretched films and biaxially stretched films, with biaxially stretched films being preferred. Examples of stretching methods for forming biaxially stretched films include sequential biaxial stretching, inflation, and simultaneous biaxial stretching. Examples of methods for applying a resin include roll coating, gravure coating, and extrusion coating.

[0022] Examples of resins that form the base layer 1 include polyester, polyamide, polyolefin, epoxy resin, acrylic resin, fluororesin, polyurethane, silicone resin, and phenolic resin, as well as modified versions of these resins. The resin that forms the base layer 1 may also be a copolymer of these resins or a modified version of the copolymer. Furthermore, it may also be a mixture of these resins.

[0023] Of these, preferred resins for forming the base layer 1 include polyester and polyamide.

[0024] Specific examples of polyesters include polyethylene terephthalate, polybutylene terephthalate, polyethylene naphthalate, polybutylene naphthalate, polyethylene isophthalate, and copolymer polyesters. Examples of copolymer polyesters include copolymer polyesters in which ethylene terephthalate is the main repeating unit. Specific examples include copolymer polyesters in which ethylene terephthalate is the main repeating unit and is polymerized with ethylene isophthalate (hereinafter abbreviated as polyethylene (terephthalate / isophthalate)), polyethylene (terephthalate / adipate), polyethylene (terephthalate / sodium sulfoisophthalate), polyethylene (terephthalate / sodium isophthalate), polyethylene (terephthalate / phenyl-dicarboxylate), and polyethylene (terephthalate / decanedicarboxylate). These polyesters may be used alone or in combination of two or more.

[0025] Specific examples of polyamides include aliphatic polyamides such as nylon 6, nylon 66, nylon 610, nylon 12, nylon 46, and copolymers of nylon 6 and nylon 66; hexamethylenediamine-isophthalic acid-terephthalic acid copolymer polyamides such as nylon 6I, nylon 6T, nylon 6IT, and nylon 6I6T (where I represents isophthalic acid and T represents terephthalic acid), which contain structural units derived from terephthalic acid and / or isophthalic acid; and aromatic polyamides such as polyamide MXD6 (polymetaxylylene adipamide); alicyclic polyamides such as polyamide PACM6 (polybis(4-aminocyclohexyl)methane adipamide); polyamides copolymerized with a lactam component or an isocyanate component such as 4,4'-diphenylmethane diisocyanate; polyesteramide copolymers and polyetheresteramide copolymers, which are copolymers of copolymerized polyamides with polyesters or polyalkylene ether glycols; and polyamides such as copolymers of these. These polyamides may be used alone or in combination of two or more.

[0026] The base layer 1 preferably includes at least one of a polyester film, a polyamide film, and a polyolefin film, preferably includes at least one of a stretched polyester film, a stretched polyamide film, and a stretched polyolefin film, more preferably includes at least one of a stretched polyethylene terephthalate film, a stretched polybutylene terephthalate film, a stretched nylon film, and a stretched polypropylene film, and even more preferably includes at least one of a biaxially oriented polyethylene terephthalate film, a biaxially oriented polybutylene terephthalate film, a biaxially oriented nylon film, and a biaxially oriented polypropylene film.

[0027] The base material layer 1 may be a single layer, or may be composed of two or more layers. When the base material layer 1 is composed of two or more layers, the base material layer 1 may be a laminate in which resin films are laminated with an adhesive or the like, or a laminate of resin films formed by co-extrusion of resins into two or more layers. Furthermore, a laminate of resin films formed by co-extrusion of resins into two or more layers may be used as the base material layer 1 without being stretched, or may be uniaxially or biaxially stretched to form the base material layer 1.

[0028] Specific examples of laminates of two or more resin films in the base layer 1 include laminates of polyester film and nylon film, laminates of two or more nylon films, and laminates of two or more polyester films. Preferably, laminates of stretched nylon film and stretched polyester film, laminates of two or more stretched nylon films, and laminates of two or more stretched polyester films are preferred. For example, when the base layer 1 is a laminate of two resin films, a laminate of polyester resin film and polyester resin film, a laminate of polyamide resin film and polyamide resin film, or a laminate of polyester resin film and polyamide resin film is preferred. A laminate of polyethylene terephthalate film and polyethylene terephthalate film, a laminate of nylon film and nylon film, or a laminate of polyethylene terephthalate film and nylon film is more preferred. Furthermore, when the base layer 1 is a laminate of two or more resin films, it is preferred that the polyester resin film be located as the outermost layer of the base layer 1, because polyester resins are less likely to discolor when an electrolyte solution adheres to their surface.

[0029] When the base layer 1 is a laminate of two or more resin film layers, the two or more resin film layers may be laminated via an adhesive. Examples of preferred adhesives include the same adhesives as those exemplified for adhesive layer 2 described below. The method for laminating two or more resin film layers is not particularly limited, and known methods can be used, such as dry lamination, sandwich lamination, extrusion lamination, and thermal lamination, with dry lamination being preferred. When laminating by dry lamination, a polyurethane adhesive is preferably used as the adhesive. In this case, the thickness of the adhesive may be, for example, about 2 to 5 μm. Alternatively, an anchor coat layer may be formed on the resin film before lamination. Examples of the anchor coat layer include the same adhesives as those exemplified for adhesive layer 2 described below. In this case, the thickness of the anchor coat layer may be, for example, about 0.01 to 1.0 μm.

[0030] Furthermore, additives such as lubricants, flame retardants, antiblocking agents, antioxidants, light stabilizers, tackifiers, and antistatic agents may be present on at least one of the surface and the interior of the base material layer 1. Only one type of additive may be used, or two or more types may be mixed and used.

[0031] In the present disclosure, from the viewpoint of improving the formability of the exterior material for an electrical storage device, it is preferable that a lubricant be present on the surface of the base layer 1. The lubricant is not particularly limited, but preferably an amide-based lubricant is used. Specific examples of amide-based lubricants include saturated fatty acid amides, unsaturated fatty acid amides, substituted amides, methylolamides, saturated fatty acid bisamides, unsaturated fatty acid bisamides, fatty acid ester amides, and aromatic bisamides. Specific examples of saturated fatty acid amides include lauric acid amide, palmitic acid amide, stearic acid amide, behenic acid amide, and hydroxystearic acid amide. Specific examples of unsaturated fatty acid amides include oleic acid amide and erucic acid amide. Specific examples of substituted amides include N-oleyl palmitic acid amide, N-stearyl stearic acid amide, N-stearyl oleic acid amide, N-oleyl stearic acid amide, and N-stearyl erucic acid amide. Specific examples of methylolamides include methylol stearic acid amide. Specific examples of saturated fatty acid bisamides include methylene bisstearic acid amide, ethylene biscapric acid amide, ethylene bislauric acid amide, ethylene bisstearic acid amide, ethylene bishydroxystearic acid amide, ethylene bisbehenic acid amide, hexamethylene bisstearic acid amide, hexamethylene bisbehenic acid amide, hexamethylene hydroxystearic acid amide, N,N'-distearyl adipamide, and N,N'-distearyl sebacic acid amide. Specific examples of unsaturated fatty acid bisamides include ethylene bisoleic acid amide, ethylene biserucic acid amide, hexamethylene bisoleic acid amide, N,N'-dioleyl adipamide, and N,N'-dioleyl sebacic acid amide. Specific examples of fatty acid ester amides include stearamidoethyl stearate. Specific examples of aromatic bisamides include m-xylylene bisstearic acid amide, m-xylylene bishydroxystearic acid amide, N,N'-distearyl isophthalic acid amide, etc. The lubricants may be used singly or in combination of two or more.

[0032] When a lubricant is present on the surface of the base layer 1, the amount of the lubricant is not particularly limited, but is preferably about 3 mg / m 2 or more, more preferably 4 to 15 mg / m 2 approximately, more preferably 5 to 14 mg / m 2 The degree of

[0033] The lubricant present on the surface of the base layer 1 may be a lubricant exuded from the resin that constitutes the base layer 1, or a lubricant applied to the surface of the base layer 1.

[0034] The thickness of the base layer 1 is not particularly limited as long as it functions as a base, but may be, for example, about 3 to 50 μm, and preferably about 10 to 35 μm. When the base layer 1 is a laminate of two or more resin films, the thickness of each resin film constituting each layer may be, for example, about 2 to 35 μm, and preferably about 2 to 25 μm.

[0035] [Adhesive layer 2] In the packaging material for an electricity storage device of the present disclosure, the adhesive layer 2 is a layer that is provided between the base layer 1 and the barrier layer 3 as needed for the purpose of increasing the adhesion between them.

[0036] The adhesive layer 2 is formed from an adhesive capable of bonding the base material layer 1 and the barrier layer 3. There are no limitations on the adhesive used to form the adhesive layer 2, and it may be any of a chemical reaction type, a solvent evaporation type, a hot melt type, a hot pressure type, etc. It may also be a two-component curing adhesive (two-component adhesive), a one-component curing adhesive (one-component adhesive), or a resin that does not involve a curing reaction. The adhesive layer 2 may be a single layer or multiple layers.

[0037] Specific examples of adhesive components contained in the adhesive include polyesters such as polyethylene terephthalate, polybutylene terephthalate, polyethylene naphthalate, polybutylene naphthalate, polyethylene isophthalate, and copolymer polyesters; polyethers; polyurethanes; epoxy resins; phenolic resins; polyamides such as nylon 6, nylon 66, nylon 12, and copolymer polyamides; polyolefin-based resins such as polyolefins, cyclic polyolefins, acid-modified polyolefins, and acid-modified cyclic polyolefins; polyvinyl acetate; cellulose; (meth)acrylic resins; polyimides; polycarbonates; amino resins such as urea resins and melamine resins; rubbers such as chloroprene rubber, nitrile rubber, and styrene-butadiene rubber; and silicone resins. These adhesive components may be used alone or in combination. Among these adhesive components, polyurethane adhesives are preferred. Furthermore, the adhesive strength of these adhesive component resins can be increased by using an appropriate curing agent in combination. The curing agent is selected appropriately from polyisocyanates, multifunctional epoxy resins, oxazoline group-containing polymers, polyamine resins, acid anhydrides, and the like, depending on the functional groups of the adhesive components.

[0038] Examples of polyurethane adhesives include polyurethane adhesives containing a base agent containing a polyol compound and a curing agent containing an isocyanate compound. Preferred examples include two-component curing polyurethane adhesives that use a polyol such as polyester polyol, polyether polyol, or acrylic polyol as the base agent and an aromatic or aliphatic polyisocyanate as the curing agent. Furthermore, as the polyol compound, it is preferable to use a polyester polyol that has hydroxyl groups on the side chain in addition to the terminal hydroxyl groups of the repeating unit. Forming the adhesive layer 2 from a polyurethane adhesive provides the electrical storage device exterior material with excellent electrolyte resistance, preventing peeling of the base layer 1 even when the electrolyte adheres to the side surface.

[0039] Furthermore, the adhesive layer 2 may contain other components as long as they do not impair adhesion, and may contain colorants, thermoplastic elastomers, tackifiers, fillers, and the like. When the adhesive layer 2 contains a colorant, the exterior material for an electricity storage device can be colored. Known colorants such as pigments and dyes can be used as the colorant. Furthermore, only one type of colorant may be used, or two or more types may be mixed together.

[0040] The type of pigment is not particularly limited as long as it does not impair the adhesiveness of the adhesive layer 2. Examples of organic pigments include azo-based, phthalocyanine-based, quinacridone-based, anthraquinone-based, dioxazine-based, indigothioindigo-based, perinone-perylene-based, isoindolenine-based, and benzimidazolone-based pigments, while examples of inorganic pigments include carbon black-based, titanium oxide-based, cadmium-based, lead-based, chromium oxide-based, and iron-based pigments, and other examples include finely powdered mica and fish scale foil.

[0041] Among colorants, carbon black is preferred in order to give the exterior appearance of the electrical storage device packaging material a black color, for example.

[0042] The average particle size of the pigment is not particularly limited and may be, for example, about 0.05 to 5 μm, and preferably about 0.08 to 2 μm. The average particle size of the pigment is the median size measured with a laser diffraction / scattering particle size distribution measuring device.

[0043] The content of the pigment in the adhesive layer 2 is not particularly limited as long as it colors the packaging material for an electricity storage device, and may be, for example, about 5 to 60 mass %, and preferably 10 to 40 mass %.

[0044] The thickness of the adhesive layer 2 is not particularly limited as long as it can bond the base layer 1 and the barrier layer 3 together, but examples thereof include approximately 1 μm or more, approximately 2 μm or more, and approximately 10 μm or less, approximately 5 μm or less, and preferred ranges include approximately 1 to 10 μm, approximately 1 to 5 μm, approximately 2 to 10 μm, and approximately 2 to 5 μm.

[0045] [Colored layer] The colored layer is a layer (not shown) that is provided between the base material layer 1 and the barrier layer 3 as needed. When the adhesive layer 2 is provided, a colored layer may be provided between the base material layer 1 and the adhesive layer 2, or between the adhesive layer 2 and the barrier layer 3. Alternatively, a colored layer may be provided on the outside of the base material layer 1. By providing a colored layer, the packaging material for an electricity storage device can be colored.

[0046] The colored layer can be formed, for example, by applying ink containing a colorant to the surface of the base layer 1, the surface of the adhesive layer 2, or the surface of the barrier layer 3. Known colorants such as pigments and dyes can be used. Furthermore, only one type of colorant may be used, or two or more types may be mixed together.

[0047] Specific examples of the colorant contained in the colored layer include the same as those described in the section [Adhesive layer 2].

[0048] [Barrier layer 3] In the packaging material for an electricity storage device, the barrier layer 3 is a layer that at least prevents the penetration of moisture.

[0049] Examples of the barrier layer 3 include metal foils, vapor-deposited films, and resin layers having barrier properties. Vapor-deposited films include metal vapor-deposited films, inorganic oxide vapor-deposited films, and carbon-containing inorganic oxide vapor-deposited films. Resin layers include fluorine-containing resins such as polyvinylidene chloride, polymers mainly composed of chlorotrifluoroethylene (CTFE), polymers mainly composed of tetrafluoroethylene (TFE), polymers having fluoroalkyl groups, and polymers mainly composed of fluoroalkyl units, as well as ethylene-vinyl alcohol copolymers. Examples of the barrier layer 3 also include resin films comprising at least one of these vapor-deposited films and resin layers. The barrier layer 3 may comprise multiple layers. The barrier layer 3 preferably includes a layer composed of a metal material. Specific examples of metal materials constituting the barrier layer 3 include aluminum alloys, stainless steel, titanium steel, and steel plates. When used as a metal foil, the barrier layer 3 preferably includes at least one of aluminum alloy foil and stainless steel foil.

[0050] From the viewpoint of improving the formability of the electrical storage device packaging material, the aluminum alloy foil is preferably a soft aluminum alloy foil made of, for example, an annealed aluminum alloy, and from the viewpoint of further improving formability, an iron-containing aluminum alloy foil is preferred. In the iron-containing aluminum alloy foil (100% by mass), the iron content is preferably 0.1 to 9.0% by mass, more preferably 0.5 to 2.0% by mass. By setting the iron content to 0.1% by mass or more, an electrical storage device packaging material with better formability can be obtained. By setting the iron content to 9.0% by mass or less, an electrical storage device packaging material with better flexibility can be obtained. Examples of soft aluminum alloy foils include aluminum alloy foils having a composition specified in JIS H4160:1994 A8021H-O, JIS H4160:1994 A8079H-O, JIS H4000:2014 A8021P-O, or JIS H4000:2014 A8079P-O. Silicon, magnesium, copper, manganese, etc. may be added as needed. Softening can be achieved by annealing or other methods.

[0051] Examples of stainless steel foil include austenitic, ferritic, austenitic-ferritic, martensitic, and precipitation hardened stainless steel foils. From the viewpoint of providing an exterior material for an electricity storage device that has excellent formability, the stainless steel foil is preferably made of austenitic stainless steel.

[0052] Specific examples of austenitic stainless steels that can be used to form the stainless steel foil include SUS304, SUS301, and SUS316L, with SUS304 being particularly preferred.

[0053] In the case of a metal foil, the thickness of the barrier layer 3 should be sufficient to at least function as a barrier layer that prevents moisture penetration, and is, for example, about 9 to 200 μm. The thickness of the barrier layer 3 is, for example, preferably about 85 μm or less, more preferably about 50 μm or less, even more preferably about 40 μm or less, and particularly preferably about 35 μm or less, and is preferably about 10 μm or more, even more preferably about 20 μm or more, and more preferably about 25 μm or more. Preferred ranges for the thickness include about 10 to 85 μm, about 10 to 50 μm, about 10 to 40 μm, about 10 to 35 μm, about 20 to 85 μm, about 20 to 50 μm, about 20 to 40 μm, about 20 to 35 μm, about 25 to 85 μm, about 25 to 50 μm, about 25 to 40 μm, and about 25 to 35 μm. The above-mentioned ranges are particularly preferred when the barrier layer 3 is made of an aluminum alloy foil. In particular, when the barrier layer 3 is made of a stainless steel foil, the thickness of the stainless steel foil is preferably about 60 μm or less, more preferably about 50 μm or less, even more preferably about 40 μm or less, even more preferably about 30 μm or less, and particularly preferably about 25 μm or less, and is preferably about 10 μm or more, more preferably about 15 μm or more. Preferred thickness ranges 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.

[0054] Furthermore, when the barrier layer 3 is a metal foil, it is preferable that a corrosion-resistant coating be provided on at least the surface opposite the substrate layer to prevent dissolution and corrosion. The barrier layer 3 may be provided with a corrosion-resistant coating on both sides. Here, the corrosion-resistant coating refers to a thin film formed on the surface of the barrier layer by, for example, a hydrothermal conversion treatment such as boehmite treatment, a chemical conversion treatment, anodizing treatment, a nickel or chromium plating treatment, or a corrosion prevention treatment such as applying a coating agent, to provide the barrier layer with corrosion resistance (e.g., acid resistance, alkali resistance, etc.). Specifically, the corrosion-resistant coating refers to a coating that improves the acid resistance of the barrier layer (acid-resistant coating) or a coating that improves the alkali resistance of the barrier layer (alkali-resistant coating). The corrosion-resistant coating may be formed by one type of treatment or a combination of two or more types. Furthermore, not only one layer but also multiple layers can be formed. Furthermore, among these treatments, the hydrothermal conversion treatment and anodizing treatment are treatments that dissolve the metal foil surface with a treatment agent to form a metal compound with excellent corrosion resistance. These treatments may be included in the definition of chemical conversion treatment. In addition, when the barrier layer 3 is provided with a corrosion-resistant coating, the barrier layer 3 includes the corrosion-resistant coating.

[0055] The corrosion-resistant coating prevents delamination between the barrier layer (e.g., aluminum alloy foil) and the substrate layer during molding of the exterior packaging material for an electricity storage device, prevents dissolution and corrosion of the barrier layer surface due to hydrogen fluoride produced by the reaction between the electrolyte and water, and in particular prevents dissolution and corrosion of aluminum oxide present on the barrier layer surface when the barrier layer is an aluminum alloy foil, and also improves the adhesion (wettability) of the barrier layer surface, thereby preventing delamination between the substrate layer and the barrier layer during heat sealing and between the substrate layer and the barrier layer during molding.

[0056] Various corrosion-resistant coatings formed by chemical conversion treatments are known, including corrosion-resistant coatings containing at least one of phosphates, chromates, fluorides, triazine thiol compounds, and rare earth oxides. Examples of chemical conversion treatments using phosphates and chromates include chromate chromate treatment, phosphate chromate treatment, phosphate-chromate treatment, and chromate treatment. Examples of chromium compounds used in these treatments include chromium nitrate, chromium fluoride, chromium sulfate, chromium acetate, chromium oxalate, chromium biphosphate, chromate acetylacetate, chromium chloride, and potassium chromium sulfate. Examples of phosphorus compounds used in these treatments include sodium phosphate, potassium phosphate, ammonium phosphate, and polyphosphoric acid. Examples of chromate treatments include etching chromate treatment, electrolytic chromate treatment, and paint-on chromate treatment, with paint-on chromate treatment being preferred. This paint-type chromate treatment involves first degreasing at least the inner surface of a barrier layer (e.g., an aluminum alloy foil) using a well-known method such as alkali immersion, electrolytic cleaning, acid pickling, electrolytic pickling, or acid activation, and then coating the degreased surface with a treatment solution primarily composed of a metal phosphate such as chromium (Cr) phosphate, titanium (Ti) phosphate, zirconium (Zr) phosphate, or zinc (Zn) phosphate, or a mixture of these metal salts, or a treatment solution primarily composed of a nonmetallic phosphate and a mixture of these nonmetallic salts, or a mixture of these with a synthetic resin, using a well-known coating method such as roll coating, gravure printing, or immersion, followed by drying. The treatment solution can be, for example, water, alcoholic solvents, hydrocarbon solvents, ketone solvents, ester solvents, or ether solvents, with water being preferred. The resin component used here may be a polymer such as a phenolic resin or an acrylic resin, or may be a chromate treatment using an aminated phenol polymer having repeating units represented by the following general formulas (1) to (4): In the aminated phenol polymer, the repeating units represented by the following general formulas (1) to (4) may be contained alone or in any combination of two or more types.The acrylic resin is preferably polyacrylic acid, an acrylic acid methacrylic acid ester copolymer, an acrylic acid maleic acid copolymer, an acrylic acid styrene copolymer, or a derivative thereof such as a sodium salt, an ammonium salt, or an amine salt. A derivative of polyacrylic acid, such as an ammonium salt, a sodium salt, or an amine salt of polyacrylic acid, is particularly preferred. In the present disclosure, polyacrylic acid refers to a polymer of acrylic acid. The acrylic resin is also preferably a copolymer of acrylic acid and a dicarboxylic acid or a dicarboxylic acid anhydride, or an ammonium salt, a sodium salt, or an amine salt of a copolymer of acrylic acid and a dicarboxylic acid or a dicarboxylic acid anhydride. Only one type of acrylic resin may be used, or two or more types may be mixed and used.

[0057] [ka]

[0058] [ka]

[0059] [ka]

[0060] [ka]

[0061] In the general formulas (1) to (4), X represents a hydrogen atom, a hydroxy group, an alkyl group, a hydroxyalkyl group, an allyl group, or a benzyl group. 1 and R 2 are the same or different and represent a hydroxy group, an alkyl group, or a hydroxyalkyl group. 1 and R 2Examples of the alkyl group represented by X and R include linear or branched alkyl groups having 1 to 4 carbon atoms, such as methyl, ethyl, n-propyl, isopropyl, n-butyl, isobutyl, and tert-butyl. 1 and R 2 Examples of the hydroxyalkyl group represented by the formula (1) include a linear or branched alkyl group having 1 to 4 carbon atoms substituted with one hydroxy group, such as a hydroxymethyl group, a 1-hydroxyethyl group, a 2-hydroxyethyl group, a 1-hydroxypropyl group, a 2-hydroxypropyl group, a 3-hydroxypropyl group, a 1-hydroxybutyl group, a 2-hydroxybutyl group, a 3-hydroxybutyl group, and a 4-hydroxybutyl group. 1 and R 2 The alkyl group and hydroxyalkyl group represented by the formula (1) may be the same or different. In the formulas (1) to (4), X is preferably a hydrogen atom, a hydroxy group, or a hydroxyalkyl group. The number average molecular weight of the aminated phenol polymer having repeating units represented by the formulas (1) to (4) is preferably about 500 to 1,000,000, and more preferably about 1,000 to 20,000. The aminated phenol polymer can be prepared, for example, by polycondensing a phenol compound or a naphthol compound with formaldehyde to produce a polymer comprising repeating units represented by the formula (1) or (3), and then polycondensing the polymer with formaldehyde and an amine (R 1 R 2 NH) to the functional group (-CHNR 1 R 2 The aminated phenol polymers can be used singly or in combination of two or more.

[0062] Another example of a corrosion-resistant coating is a thin film formed by a coating-type corrosion prevention treatment in which a coating agent containing at least one selected from the group consisting of a rare earth element oxide sol, an anionic polymer, and a cationic polymer is applied. The coating agent may further contain phosphoric acid or a phosphate salt, and a crosslinking agent for crosslinking the polymer. The rare earth element oxide sol has rare earth element oxide fine particles (e.g., particles with an average particle size of 100 nm or less) dispersed in a liquid dispersion medium. Examples of rare earth element oxides include cerium oxide, yttrium oxide, neodymium oxide, and lanthanum oxide, with cerium oxide being preferred from the perspective of further improving adhesion. The rare earth element oxide contained in the corrosion-resistant coating can be used alone or in combination of two or more. The liquid dispersion medium for the rare earth element oxide sol can be various solvents such as water, alcohol-based solvents, hydrocarbon-based solvents, ketone-based solvents, ester-based solvents, and ether-based solvents, with water being preferred. Preferred examples of cationic polymers include polyethyleneimine, ionic polymer complexes composed of polyethyleneimine and a polymer having a carboxylic acid, primary amine-grafted acrylic resins in which a primary amine is graft-polymerized onto an acrylic backbone, polyallylamine or its derivatives, and aminated phenols. Preferred anionic polymers are poly(meth)acrylic acid or its salts, or copolymers primarily composed of (meth)acrylic acid or its salts. The crosslinking agent is preferably at least one selected from the group consisting of a compound having a functional group selected from an isocyanate group, a glycidyl group, a carboxyl group, and an oxazoline group, and a silane coupling agent. The phosphoric acid or phosphoric acid salt is preferably a condensed phosphoric acid or a condensed phosphate salt.

[0063] An example of a corrosion-resistant coating is one formed by applying a solution of fine particles of metal oxides such as aluminum oxide, titanium oxide, cerium oxide, and tin oxide, or barium sulfate dispersed in phosphoric acid to the surface of a barrier layer and baking the coating at 150°C or higher.

[0064] The corrosion-resistant coating may have a laminated structure, if necessary, by further laminating at least one of a cationic polymer and an anionic polymer, such as those mentioned above.

[0065] The composition of the corrosion-resistant film can be analyzed using, for example, time-of-flight secondary ion mass spectrometry.

[0066] The amount of the corrosion-resistant film formed on the surface of the barrier layer 3 in the chemical conversion treatment is not particularly limited. For example, in the case of applying chromate treatment, the amount of the corrosion-resistant film formed on the surface of the barrier layer 3 is 2 It is desirable that the chromate compound is contained in an amount, in terms of chromium, of about 0.5 to 50 mg, preferably about 1.0 to 40 mg, the phosphorus compound in terms of phosphorus, and the aminated phenol polymer in an amount, in terms of phosphorus, of about 1.0 to 200 mg, preferably about 5.0 to 150 mg, per unit area.

[0067] The thickness of the corrosion-resistant coating is not particularly limited, but is preferably about 1 nm to 20 μm, more preferably about 1 nm to 100 nm, and even more preferably about 1 nm to 50 nm, from the viewpoint of the cohesive strength of the coating and the adhesive strength with the barrier layer and the thermally adhesive resin layer. The thickness of the corrosion-resistant coating can be measured by observation with a transmission electron microscope, or by a combination of observation with a transmission electron microscope and energy dispersive X-ray spectroscopy or electron energy loss spectroscopy. Analysis of the composition of the corrosion-resistant coating using time-of-flight secondary ion mass spectrometry can reveal the thickness of the corrosion-resistant coating, for example, by measuring the thickness of the corrosion-resistant coating with secondary ions consisting of Ce, P, and O (e.g., Ce2PO4 + , CePO4 - At least one of the following ions may be present: Cr, P, and O secondary ions (e.g., CrPO2 + , CrPO4 - Peaks derived from at least one of the above are detected.

[0068] The chemical conversion treatment is carried out by applying a solution containing a compound used to form a corrosion-resistant coating to the surface of the barrier layer by bar coating, roll coating, gravure coating, immersion, or other methods, and then heating the barrier layer to a temperature of approximately 70 to 200°C. Furthermore, before applying the chemical conversion treatment to the barrier layer, the barrier layer may be subjected to a degreasing treatment using an alkali immersion method, electrolytic cleaning, acid cleaning, electrolytic acid cleaning, or other methods. By performing such a degreasing treatment, the chemical conversion treatment of the surface of the barrier layer can be carried out more efficiently. Furthermore, using an acid degreasing agent prepared by dissolving a fluorine-containing compound in an inorganic acid for the degreasing treatment not only degreases the metal foil but also forms a passive metal fluoride. In such cases, only the degreasing treatment may be performed.

[0069] [Thermal adhesive resin layer 4] In the packaging material for an electricity storage device of the present disclosure, the heat-sealable resin layer 4 is located on the inner layer side and is a layer (sealant layer) that functions to seal the electricity storage device elements by heat-sealing the heat-sealable resin layer when the electricity storage device is assembled. In the packaging material 10 for an electricity storage device of the present disclosure, the heat-sealable resin layer 4 is composed of a single layer or multiple layers, and of the heat-sealable resin layer 4, the first heat-sealable resin layer 41 forms the surface of the laminate. Therefore, when the electricity storage device is assembled, the first heat-sealable resin layer 41 is heat-sealed to seal the electricity storage device elements.

[0070] When the heat-sealable resin layer 4 is configured as a single layer, the heat-sealable resin layer 4 constitutes a first heat-sealable resin layer 41. Figures 1 and 2 show a laminated structure in which the heat-sealable resin layer 4 is configured as a single layer of the first heat-sealable resin layer 41, and the first heat-sealable resin layer 41 constitutes the surface of the laminate.

[0071] Furthermore, when the heat-sealable resin layer 4 is configured as multiple layers, it has at least a first heat-sealable resin layer 41 and a second heat-sealable resin layer 42, in that order from the surface side of the laminate that constitutes the packaging material 10 for an electricity storage device. Figures 3 to 5 show a laminate configuration in which the heat-sealable resin layer 4 is configured as multiple layers (two layers) of the first heat-sealable resin layer 41 and the second heat-sealable resin layer 42, and the first heat-sealable resin layer 41 forms the surface of the laminate.

[0072] When the heat-sealable resin layer 4 is configured as multiple layers, the heat-sealable resin layer 4 may further include a third heat-sealable resin layer, a fourth heat-sealable resin layer, etc. on the barrier layer 3 side of the second heat-sealable resin layer 42 in addition to the first heat-sealable resin layer 41 and the second heat-sealable resin layer 42. When the heat-sealable resin layer 4 is configured as multiple layers, the heat-sealable resin layer 4 is preferably configured as two layers, the first heat-sealable resin layer 41 and the second heat-sealable resin layer 42.

[0073] The packaging material for an electricity storage device according to the present disclosure is characterized in that the logarithmic decrement ΔE at 140°C in rigid pendulum measurement of the first heat-sealable resin layer 41 is 0.20 or less. In the present disclosure, since the logarithmic decrement ΔE at 140°C is 0.20 or less, collapse when the first heat-sealable resin layer 41 is heat-sealed is effectively suppressed.

[0074] The logarithmic decrement at 140°C in rigid pendulum measurements is an index of the hardness of a resin in a high-temperature environment of 140°C. A smaller logarithmic decrement indicates a higher resin hardness. The temperature used for heat-sealing a heat-sealable resin layer is high, and the heat-sealed portion formed by heat-sealing the heat-sealable resin layer may significantly protrude into the heat-sealed portion (the space where the energy storage device element is housed) at the heat-sealed portion. If the heat-sealable resin layer 4 significantly protrudes into the heat-sealed portion, cracks may form in the heat-sealed resin layer 4 from the protrusion (a so-called "polyethylene pool"), resulting in a decrease in insulation. Figure 11 shows a schematic cross-sectional view of a heat-sealable resin layer 4 with a protrusion A formed inside the heat-sealed portion. As shown in this cross-sectional view, the protrusion A has two end points A1 and A2, which are structurally prone to become crack initiation points. Therefore, if the heat-sealable resin layer 4 significantly protrudes into the heat-sealed portion, forming a protrusion, the insulation properties are likely to deteriorate due to cracks. For this reason, it is important to control the shape of the heat-sealed portion, and for this purpose, the hardness of the heat-sealable resin layer at high temperatures is important. Therefore, in the present invention, the logarithmic attenuation rate at a high temperature of 140°C is used. In rigid pendulum measurements, the attenuation rate of the pendulum is measured as the resin temperature is increased from a low temperature to a high temperature. In rigid pendulum measurements, the edge portion is generally brought into contact with the surface of the object to be measured, and the object is caused to swing back and forth, thereby vibrating. In the electrical storage device packaging material of the present invention, a hard first heat-sealable resin layer 41 having a logarithmic attenuation rate of 0.20 or less at a high temperature of 140°C is disposed on the surface of the electrical storage device packaging material, thereby suppressing collapse (thinning) of the first heat-sealable resin layer 41 during thermal fusion of the electrical storage device packaging material. By suppressing the crushing of the first heat-sealable resin layer 41, the heat-sealed portion formed by heat-sealing the heat-sealable resin layer is prevented from protruding significantly inside the heat-sealed portion, and the deterioration of the insulating properties of the exterior material for the energy storage device due to heat fusion is effectively suppressed.

[0075] The logarithmic attenuation factor ΔE is calculated by the following formula: ΔE=[ln(A1 / A2)+ln(A2 / A3)+...ln(An / An+1)] / n A: Amplitude n: wave number

[0076] In the packaging material for an electricity storage device of the present invention, from the viewpoint of effectively suppressing crushing of the first heat-sealable resin layer 41 when the first heat-sealable resin layer 41 is heat-sealed, the logarithmic decrement ΔE at 140°C is preferably about 0.10 or more, more preferably about 0.11 or more, and even more preferably about 0.12 or more, and is also preferably about 0.18 or less, more preferably about 0.15 or less, and even more preferably about 0.16 or less. or about 0.13 or less, and preferred ranges include about 0.10 to 0.20, about 0.10 to 0.18, about 0.10 to 0.15, about 0.10 to 0.13, about 0.11 to 0.20, about 0.11 to 0.18, about 0.11 to 0.15, about 0.11 to 0.13, about 0.12 to 0.20, about 0.12 to 0.18, about 0.12 to 0.15, and about 0.12 to 0.13.

[0077] Furthermore, in the packaging material for an electricity storage device of the present disclosure, from the viewpoint of effectively suppressing crushing of the first heat-sealable resin layer 41 when the first heat-sealable resin layer 41 is heat-sealed, the logarithmic decrement ΔE of the first heat-sealable resin layer 41 at 80°C in rigid pendulum measurement is preferably greater than 0.08, more preferably equal to or greater than about 0.09, and even more preferably equal to or greater than about 0.10. Furthermore, in the packaging material for an electricity storage device of the present disclosure, the logarithmic decrement ΔE of the first heat-sealable resin layer 41 at 80°C in rigid pendulum measurement is preferably equal to or less than about 0.20, more preferably equal to or less than about 0.18, and even more preferably equal to or less than about 0.15. Preferred ranges for the logarithmic decrement ΔE are greater than 0.08 and equal to or less than 0.20, greater than 0.08 and equal to or less than 0.18, greater than 0.08 and equal to or less than 0.15, approximately 0.09 to 0.20, approximately 0.09 to 0.18 degrees, approximately 0.09 to 0.15, approximately 0.10 to 0.20, approximately 0.10 to 0.18 degrees, and approximately 0.10 to 0.15.

[0078] The logarithmic decrement ΔE at 80°C in the rigid pendulum measurement of the first heat-sealable resin layer 41 is measured in the same manner as in the method for measuring the logarithmic decrement ΔE at 140°C, except that the logarithmic decrement ΔE when the surface temperature of the first heat-sealable resin layer 41 has reached 80°C is used.

[0079] The logarithmic decrement ΔE of the first heat-sealable resin layer 41 can be adjusted, for example, by the melt mass flow rate (MFR), molecular weight, melting point, softening point, molecular weight distribution, degree of crystallinity, etc. of the resin constituting the first heat-sealable resin layer 41.

[0080] The logarithmic attenuation ΔE was measured using a commercially available rigid pendulum-type physical property tester. The rigid pendulum physical property test was performed on the first heat-sealable resin layer 41 under the following conditions: a cylindrical edge was used as the edge pressed against the first heat-sealable resin layer 41; an initial amplitude of 0.3 degrees; a temperature range of 30°C to 200°C; and a heating rate of 3°C / min. Based on the logarithmic attenuation at 140°C, a standard for the collapse suppression exhibited by the first heat-sealable resin layer 41 (described below) was determined. Regarding the first heat-sealable resin layer 41 for which the logarithmic attenuation ΔE was measured, the packaging material for an electricity storage device was immersed in 15% hydrochloric acid to dissolve the base layer and barrier layer, and the resulting sample was thoroughly dried. When the packaging material for an electricity storage device includes the adhesive layer 5 (described below), a laminate of the adhesive layer 5 and the heat-sealable resin layer 4 was used as the sample.

[0081] It is also possible to obtain the electrical storage device packaging material from the electrical storage device and measure the logarithmic decrement ΔE of the first thermally adhesive resin layer 41. When obtaining the electrical storage device packaging material from the electrical storage device and measuring the logarithmic decrement ΔE of the first thermally adhesive resin layer 41, a sample is cut out from the top surface portion of the electrical storage device packaging material that has not been stretched by molding and used as the measurement object.

[0082] Furthermore, in the packaging material for an electric storage device of the present invention, the heat-sealable resin layers of the laminate constituting the packaging material for an electric storage device are placed opposite each other and heated and pressurized in the lamination direction at a temperature of 190°C, a surface pressure of 2.0 MPa, and a time of 3 seconds. After this, the remaining percentage of the total thickness of the two first heat-sealable resin layers 41 is preferably about 30% or more, more preferably about 32% or more, and more preferably about 34% or more, with preferred ranges including 30-60%, 32-60%, 34-60%, 30-50%, 32-50%, and 34-50%. The upper limit of the remaining percentage of the thickness is, for example, about 60% or about 50%. The remaining percentage of the thickness is a value measured by the following method. To achieve this remaining percentage of the thickness, for example, the type, composition, molecular weight, etc. of the resin constituting the first heat-sealable resin layer 41 are adjusted.

[0083] <Measurement of the remaining thickness of the first heat-sealable resin layer> The exterior material for an electricity storage device is cut to a length of 150 mm and a width of 60 mm to prepare a test sample. Next, the first heat-sealable resin layers 41 of the test samples are placed facing each other. Next, in this state, a 7 mm wide metal plate is used to heat and pressurize both sides of the test sample in the stacking direction at a temperature of 190°C, a surface pressure of 0.5 MPa, and a time of 3 seconds to heat-seal the first heat-sealable resin layers 41. Next, the heat-sealed portion of the test sample is cut in the stacking direction using a microtome, and the total thickness of the two first heat-sealable resin layers 41 that are heat-sealed to each other is measured for the exposed cross section. The test sample before heat-sealing is also cut in the stacking direction using a microtome in the same manner, and the thicknesses of the two first heat-sealable resin layers 41 are measured for the exposed cross section. The ratio of the total thickness of the two first heat-sealable resin layers 41 after heat-sealing to the total thickness of the two first heat-sealable resin layers 41 before heat-sealing is calculated to measure the remaining ratio (%) of the total thickness of the two first heat-sealable resin layers 41. The thicknesses of the two first heat-sealable resin layers 41 in the heat-sealed portion are measured at a location where the thickness of the exterior packaging material for an electricity storage device is constant.

[0084] It is also possible to obtain the exterior packaging material for an electricity storage device from the electricity storage device and measure the remaining proportion of the total thickness of the two first thermally adhesive resin layers 41. When obtaining the exterior packaging material for an electricity storage device from the electricity storage device and measuring the remaining proportion of the total thickness of the two first thermally adhesive resin layers 41, a sample is cut out from the top surface portion of the exterior packaging material for an electricity storage device that has not been stretched by molding and used as the measurement object.

[0085] The resin constituting the first heat-sealable resin layer 41 is not particularly limited as long as it is heat-sealable and the logarithmic decrement ΔE of the first heat-sealable resin layer 41 is 0.20 or less.

[0086] The resin constituting the first heat-sealable resin layer 41 is preferably a resin containing a polyolefin skeleton, such as polyolefin or acid-modified polyolefin. The presence of a polyolefin skeleton in the resin constituting the first heat-sealable resin layer 41 can be determined by, for example, infrared spectroscopy, gas chromatography mass spectrometry, or the like. Furthermore, when the resin constituting the first heat-sealable resin layer 41 is analyzed by infrared spectroscopy, a peak derived from maleic anhydride is preferably detected. For example, when maleic anhydride-modified polyolefin is measured by infrared spectroscopy, a peak derived from maleic anhydride is detected at a wave number of 1760 cm. -1 Near and wave number 1780cm -1 A peak derived from maleic anhydride is detected around . When the first heat-sealable resin layer 41 is a layer made of maleic anhydride-modified polyolefin, a peak derived from maleic anhydride is detected when measured by infrared spectroscopy. However, if the degree of acid modification is low, the peak becomes small and may not be detected. In such cases, analysis can be performed by nuclear magnetic resonance spectroscopy.

[0087] Specific examples of polyolefins include polyethylenes such as low-density polyethylene, medium-density polyethylene, high-density polyethylene, and linear low-density polyethylene; ethylene-α-olefin copolymers; polypropylenes such as homopolypropylene, block copolymers of polypropylene (e.g., block copolymers of propylene and ethylene), and random copolymers of polypropylene (e.g., random copolymers of propylene and ethylene); propylene-α-olefin copolymers; and ethylene-butene-propylene terpolymers. Among these, polypropylene is preferred. When the polyolefin resin is a copolymer, it may be a block copolymer or a random copolymer. These polyolefin resins may be used alone or in combination of two or more.

[0088] The polyolefin may also be a cyclic polyolefin. Cyclic polyolefins are copolymers of olefins and cyclic monomers, and examples of olefins constituting the cyclic polyolefin include ethylene, propylene, 4-methyl-1-pentene, styrene, butadiene, and isoprene. Examples of cyclic monomers constituting the cyclic polyolefin include cyclic alkenes such as norbornene; and cyclic dienes such as cyclopentadiene, dicyclopentadiene, cyclohexadiene, and norbornadiene. Among these, preferred are cyclic alkenes, and more preferred are norbornene.

[0089] Acid-modified polyolefins are polymers modified by block polymerization or graft polymerization of polyolefins with an acid component. Examples of acid-modified polyolefins include the above-mentioned polyolefins, copolymers of the above-mentioned polyolefins with polar molecules such as acrylic acid or methacrylic acid, and crosslinked polyolefins. Examples of acid components used for acid modification include carboxylic acids or anhydrides thereof, such as maleic acid, acrylic acid, itaconic acid, crotonic acid, maleic anhydride, and itaconic anhydride.

[0090] The acid-modified polyolefin may be an acid-modified cyclic polyolefin. The acid-modified cyclic polyolefin is a polymer obtained by copolymerizing a part of the monomers constituting the cyclic polyolefin by replacing it with an acid component, or by block polymerizing or graft polymerizing an acid component onto the cyclic polyolefin. The acid-modified cyclic polyolefin is the same as described above. The acid component used for the acid modification is the same as the acid component used for the modification of the polyolefin.

[0091] Preferred acid-modified polyolefins include polyolefins modified with carboxylic acid or its anhydride, polypropylenes modified with carboxylic acid or its anhydride, maleic anhydride-modified polyolefins, and maleic anhydride-modified polypropylenes.

[0092] The first heat-fusible resin layer 41 may be formed of one type of resin alone, or may be formed of a blend polymer in which two or more types of resins are combined.

[0093] The first heat-sealable resin layer 41 constituting the surface preferably contains a polyolefin. For example, in the electrical storage device packaging material 10 of the present disclosure, when the heat-sealable resin layer 4 includes a first heat-sealable resin layer 41 and a second heat-sealable resin layer 42, it is preferable that the first heat-sealable resin layer 41 constituting the surface contains a polyolefin, and the second heat-sealable resin layer 42 contains an acid-modified polyolefin. Furthermore, in the electrical storage device packaging material 10 of the present disclosure, when the adhesive layer 5 is included, it is preferable that the first heat-sealable resin layer 41 constituting the surface contains a polyolefin, and the adhesive layer 5 contains an acid-modified polyolefin. Furthermore, it is preferable that the adhesive layer 5 contains an acid-modified polyolefin, the first heat-sealable resin layer contains a polyolefin, and the second heat-sealable resin layer contains a polyolefin. It is more preferable that the adhesive layer 5 contains an acid-modified polypropylene, the first heat-sealable resin layer contains polypropylene, and the second heat-sealable resin layer contains polypropylene.

[0094] Furthermore, the first thermally adhesive resin layer 41 may contain a lubricant or the like, if necessary. When the first thermally adhesive resin layer 41 contains a lubricant, the formability of the electrical storage device packaging material can be improved. The lubricant is not particularly limited, and known lubricants can be used. The lubricants may be used alone or in combination of two or more.

[0095] The lubricant is not particularly limited, but preferably an amide-based lubricant is used. Specific examples of the lubricant include those exemplified for the base layer 1. The lubricant may be used alone or in combination of two or more.

[0096] When a lubricant is present on the surface of the first heat-sealable resin layer 41, the amount of the lubricant present is not particularly limited, but from the viewpoint of improving the formability of the packaging material for an electricity storage device, it is preferably 10 to 50 mg / m 2 about 15 to 40 mg / m 2 In addition, even when a lubricant is present on the surface of the first thermally adhesive resin layer 41, the first thermally adhesive resin layer 41, including the lubricant, forms the surface of the packaging material 10 for an electricity storage device.

[0097] The lubricant present on the surface of the first heat-sealable resin layer 41 may be a lubricant exuded from the resin constituting the first heat-sealable resin layer 41, or a lubricant applied to the surface of the first heat-sealable resin layer 41.

[0098] Furthermore, the thickness of the first heat-sealable resin layer 41 is not particularly limited as long as the heat-sealable resin layer exhibits the function of heat-sealing the electricity storage device elements.

[0099] From the viewpoint of effectively suppressing crushing when the first heat-sealable resin layer 41 is heat-sealed, the thickness of the first heat-sealable resin layer 41 is preferably about 100 μm or less, about 85 μm or less, or about 60 μm or less, and also 5 μm or more, 10 μm or more, 20 μm or more, 30 μm or more, or 40 μm or more, and preferred ranges include about 5 to 100 μm, about 5 to 85 μm, about 5 to 60 μm, about 10 to 100 μm, about 10 to 85 μm, about 10 to 60 μm, about 20 to 100 μm, about 20 to 85 μm, about 20 to 60 μm, about 30 to 100 μm, about 30 to 85 μm, about 30 to 60 μm, about 40 to 100 μm, about 40 to 85 μm, and about 40 to 60 μm.

[0100] Specifically, from the viewpoint of effectively suppressing crushing when the first heat-sealable resin layer 41 is heat-sealed, when the heat-sealable resin layer 4 is constituted by a single layer of the first heat-sealable resin layer 41, the thickness of the first heat-sealable resin layer 41 is preferably about 100 μm or less, about 85 μm or less, about 60 μm or less, or about 25 μm or less, and also preferably 5 μm or more, 10 μm or more, 20 μm or more, 30 μm or more, or 40 μm or more. Examples of the thickness include about 5 to 100 μm, about 5 to 85 μm, about 5 to 60 μm, about 5 to 25 μm, about 10 to 100 μm, about 10 to 85 μm, about 10 to 60 μm, about 10 to 25 μm, about 20 to 100 μm, about 20 to 85 μm, about 20 to 60 μm, about 20 to 25 μm, about 30 to 100 μm, about 30 to 85 μm, about 30 to 60 μm, about 40 to 100 μm, about 40 to 85 μm, and about 40 to 60 μm.

[0101] Furthermore, from the viewpoint of effectively suppressing crushing when the first heat-sealing resin layer 41 is heat-sealed and improving the sealing performance of the packaging material for an electricity storage device, when the heat-sealing resin layer 4 includes the first heat-sealing resin layer 41 and the second heat-sealing resin layer 42, the thickness of the first heat-sealing resin layer 41 is preferably about 85 μm or less, about 60 μm or less, or about 25 μm or less, and also preferably 5 μm or more, 10 μm or more. , 20 μm or more, 30 μm or more, and 40 μm or more, and preferred ranges include about 5 to 85 μm, about 5 to 60 μm, about 5 to 25 μm, about 10 to 85 μm, about 10 to 60 μm, about 10 to 25 μm, about 20 to 85 μm, about 20 to 60 μm, about 20 to 25 μm, about 30 to 85 μm, about 30 to 60 μm, about 40 to 85 μm, and about 40 to 60 μm.

[0102] When the thermally adhesive resin layer 4 includes a second thermally adhesive resin layer 42, the resin constituting the second thermally adhesive resin layer 42 is preferably a resin containing a polyolefin skeleton, such as polyolefin or acid-modified polyolefin. These resins are the same as those described for the first thermally adhesive resin layer 41. The presence of a polyolefin skeleton in the resin constituting the second thermally adhesive resin layer 42 can be determined by, for example, infrared spectroscopy, gas chromatography mass spectrometry, or the like. Furthermore, when the resin constituting the second thermally adhesive resin layer 42 is analyzed by infrared spectroscopy, a peak derived from maleic anhydride is preferably detected. For example, when maleic anhydride-modified polyolefin is measured by infrared spectroscopy, a peak derived from maleic anhydride is detected at a wavenumber of 1760 cm. -1 Near and wave number 1780cm -1 A peak derived from maleic anhydride is detected around . When the second heat-sealable resin layer 42 is a layer made of maleic anhydride-modified polyolefin, a peak derived from maleic anhydride is detected when measured by infrared spectroscopy. However, if the degree of acid modification is low, the peak becomes small and may not be detected. In such cases, analysis can be performed by nuclear magnetic resonance spectroscopy.

[0103] The second heat-sealable resin layer 42 preferably contains a polyolefin. In particular, when the heat-sealable resin layer 4 includes the first heat-sealable resin layer 41 and the second heat-sealable resin layer 42 and includes the adhesive layer 5 described below, the second heat-sealable resin layer 42 preferably contains a polyolefin. Furthermore, as described above, in the packaging material 10 for an electricity storage device according to the present disclosure, when the heat-sealable resin layer 4 includes the first heat-sealable resin layer 41 and the second heat-sealable resin layer 42 but does not include the adhesive layer 5 described below, it is preferable that the first heat-sealable resin layer 41 constituting the surface contains a polyolefin, and the second heat-sealable resin layer 42 contains an acid-modified polyolefin.

[0104] The thickness of the second heat-sealable resin layer 42 is not particularly limited as long as it can perform the function of heat-sealing the heat-sealable resin layer 4 to seal the electricity storage device elements.

[0105] From the viewpoint of effectively suppressing crushing when the first heat-sealable resin layer 41 is heat-sealed and improving the sealing performance of the electrical storage device packaging material, the thickness of the second heat-sealable resin layer 42 is preferably greater than the thickness of the first heat-sealable resin layer 41. The first heat-sealable resin layer 41 is preferably made of a resin that flows easily at high temperatures so as to have excellent thermal adhesion. By achieving this thickness relationship, the first heat-sealable resin layer 41, which is a part of the heat-sealable resin layer 4 and is made of a resin that flows easily, can be made thinner, thereby improving the insulation properties of the electrical storage device packaging material. By appropriately adjusting the MFR, melting point, molecular weight, and other properties of the resin that forms the first heat-sealable resin layer 41, the first heat-sealable resin layer 41 can be made into a resin layer that flows easily at high temperatures.

[0106] From the viewpoint of effectively suppressing crushing when the first heat-sealable resin layer 41 is heat-sealed and improving the sealing performance of the packaging material for an electricity storage device, the thickness of the second heat-sealable resin layer 42 is preferably about 100 μm or less, about 85 μm or less, or about 60 μm or less, and also preferably 5 μm or more, 10 μm or more, 20 μm or more, 30 μm or more, or 40 μm or more. Examples of the thickness include about 5 to 100 μm, about 5 to 85 μm, about 5 to 60 μm, about 10 to 100 μm, about 10 to 85 μm, about 10 to 60 μm, about 20 to 100 μm, about 20 to 85 μm, about 20 to 60 μm, about 30 to 100 μm, about 30 to 85 μm, about 30 to 60 μm, about 40 to 100 μm, about 40 to 85 μm, and about 40 to 60 μm.

[0107] The heat-sealable resin layer 4 may further include other heat-sealable resin layers, such as a third heat-sealable resin layer and a fourth heat-sealable resin layer, on the barrier layer 3 side of the second heat-sealable resin layer 42, in addition to the first heat-sealable resin layer 41 and the second heat-sealable resin layer 42. Examples of resins constituting the other heat-sealable resin layers include the same resins as those described for the first heat-sealable resin layer 41. Examples of thicknesses of the other heat-sealable resin layers include the same thicknesses as those described for the second heat-sealable resin layer 42.

[0108] The total thickness of the heat-sealable resin layer 4 is preferably about 100 μm or less, about 85 μm or less, or about 60 μm or less, and also 5 μm or more, 10 μm or more, 20 μm or more, 30 μm or more, or 40 μm or more, and preferred ranges include about 5 to 100 μm, about 5 to 85 μm, about 5 to 60 μm, about 10 to 100 μm, about 10 to 85 μm, about 10 to 60 μm, about 20 to 100 μm, about 20 to 85 μm, about 20 to 60 μm, about 30 to 100 μm, about 30 to 85 μm, about 30 to 60 μm, about 40 to 100 μm, about 40 to 85 μm, and about 40 to 60 μm.

[0109] [Adhesive layer 5] In the packaging material for an electricity storage device of the present disclosure, the adhesive layer 5 is a layer that is provided as needed between the barrier layer 3 (or corrosion-resistant film) and the heat-sealable resin layer 4 in order to firmly bond them together.

[0110] The adhesive layer 5 is formed of a resin capable of bonding the barrier layer 3 and the heat-sealable resin layer 4. The resin used to form the adhesive layer 5 can be, for example, the same adhesive as exemplified for the adhesive layer 2. The resin used to form the adhesive layer 5 preferably contains a polyolefin skeleton, such as the polyolefins and acid-modified polyolefins exemplified for the first heat-sealable resin layer 41. The presence of a polyolefin skeleton in the resin constituting the adhesive layer 5 can be determined by, for example, infrared spectroscopy or gas chromatography-mass spectrometry, and no particular analytical method is required. Furthermore, when the resin constituting the adhesive layer 5 is analyzed by infrared spectroscopy, a peak derived from maleic anhydride is preferably detected. For example, when a maleic anhydride-modified polyolefin is measured by infrared spectroscopy, a peak derived from maleic anhydride is detected at a wavenumber of 1760 cm. -1 Near and wave number 1780cm -1 A peak derived from maleic anhydride is detected around this point. However, if the degree of acid modification is low, the peak may be small and not be detected. In this case, analysis can be performed using nuclear magnetic resonance spectroscopy.

[0111] The adhesive layer 5 can be formed from a thermoplastic resin or a cured product of a thermosetting resin, and is preferably formed from a thermoplastic resin.

[0112] From the viewpoint of firmly bonding the barrier layer 3 and the heat-sealable resin layer 4, the adhesive layer 5 preferably contains an acid-modified polyolefin. Particularly preferred examples of the acid-modified polyolefin include polyolefins modified with carboxylic acid or its anhydride, polypropylenes modified with carboxylic acid or its anhydride, maleic anhydride-modified polyolefins, and maleic anhydride-modified polypropylenes.

[0113] Furthermore, from the viewpoint of reducing the thickness of the electrical storage device packaging material while providing an electrical storage device packaging material that has excellent shape stability after molding, the adhesive layer 5 is more preferably a cured product of a resin composition containing an acid-modified polyolefin and a curing agent. Preferred examples of the acid-modified polyolefin include those mentioned above.

[0114] As described above, when the packaging material 10 for an electricity storage device of the present disclosure has an adhesive layer 5, it is preferable that the first heat-sealable resin layer 41 constituting the surface contains a polyolefin, and the adhesive layer 5 contains an acid-modified polyolefin.

[0115] The adhesive layer 5 is preferably a cured product of a resin composition containing an acid-modified polyolefin and at least one selected from the group consisting of a compound having an isocyanate group, a compound having an oxazoline group, and a compound having an epoxy group. It is particularly preferably a cured product of a resin composition containing an acid-modified polyolefin and at least one selected from the group consisting of a compound having an isocyanate group and a compound having an epoxy group. The adhesive layer 5 preferably contains at least one selected from the group consisting of polyurethane, polyester, and epoxy resin, more preferably polyurethane and epoxy resin. A preferred polyester is, for example, an amide ester resin. Amide ester resins are generally produced by the reaction of a carboxyl group with an oxazoline group. The adhesive layer 5 is more preferably a cured product of a resin composition containing at least one of these resins and the acid-modified polyolefin. In addition, if unreacted compounds of curing agents such as compounds having an isocyanate group, compounds having an oxazoline group, and epoxy resins remain in the adhesive layer 5, the presence of the unreacted compounds can be confirmed by a method selected from, for example, infrared spectroscopy, Raman spectroscopy, time-of-flight secondary ion mass spectrometry (TOF-SIMS), etc.

[0116] Furthermore, from the viewpoint of further enhancing the adhesion between the barrier layer 3 and the adhesive layer 5, the adhesive layer 5 is preferably a cured product of a resin composition containing a curing agent having at least one selected from the group consisting of an oxygen atom, a heterocycle, a C═N bond, and a COC bond. Examples of curing agents having a heterocycle include curing agents having an oxazoline group and curing agents having an epoxy group. Examples of curing agents having a C═N bond include curing agents having an oxazoline group and curing agents having an isocyanate group. Examples of curing agents having a COC bond include curing agents having an oxazoline group, curing agents having an epoxy group, and polyurethane. Whether the adhesive layer 5 is a cured product of a resin composition containing such a curing agent can be confirmed by, for example, gas chromatography mass spectrometry (GCMS), infrared spectroscopy (IR), time-of-flight secondary ion mass spectrometry (TOF-SIMS), X-ray photoelectron spectroscopy (XPS), or other methods.

[0117] The compound having an isocyanate group is not particularly limited, but from the viewpoint of effectively improving the adhesion between the barrier layer 3 and the adhesive layer 5, a polyfunctional isocyanate compound is preferably used. The polyfunctional isocyanate compound is not particularly limited as long as it is a compound having two or more isocyanate groups. Specific examples of polyfunctional isocyanate curing agents include pentane diisocyanate (PDI), isophorone diisocyanate (IPDI), hexamethylene diisocyanate (HDI), tolylene diisocyanate (TDI), diphenylmethane diisocyanate (MDI), polymers or nurates thereof, mixtures of these, and copolymers with other polymers. Other examples include adducts, biuret compounds, and isocyanurates.

[0118] The content of the compound having an isocyanate group in the adhesive layer 5 is preferably in the range of 0.1 to 50 mass %, and more preferably in the range of 0.5 to 40 mass %, of the resin composition constituting the adhesive layer 5. This can effectively improve the adhesion between the barrier layer 3 and the adhesive layer 5.

[0119] The compound having an oxazoline group is not particularly limited as long as it is a compound having an oxazoline skeleton. Specific examples of the compound having an oxazoline group include those having a polystyrene main chain and those having an acrylic main chain. Examples of commercially available products include the Epocross series manufactured by Nippon Shokubai Co., Ltd.

[0120] The proportion of the compound having an oxazoline group in the adhesive layer 5 is preferably in the range of 0.1 to 50 mass %, and more preferably in the range of 0.5 to 40 mass %, in the resin composition constituting the adhesive layer 5. This can effectively improve the adhesion between the barrier layer 3 and the adhesive layer 5.

[0121] An example of a compound having an epoxy group is an epoxy resin. The epoxy resin is not particularly limited as long as it is a resin capable of forming a crosslinked structure by the epoxy groups present in the molecule, and known epoxy resins can be used. The weight-average molecular weight of the epoxy resin is preferably about 50 to 2,000, more preferably about 100 to 1,000, and even more preferably about 200 to 800. In the present 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.

[0122] Specific examples of epoxy resins include glycidyl ether derivatives of trimethylolpropane, bisphenol A diglycidyl ether, modified bisphenol A diglycidyl ether, novolac glycidyl ether, glycerin polyglycidyl ether, polyglycerin polyglycidyl ether, etc. One type of epoxy resin may be used alone, or two or more types may be used in combination.

[0123] The proportion of the epoxy resin in the adhesive layer 5 is preferably in the range of 0.1 to 50 mass %, and more preferably in the range of 0.5 to 40 mass %, of the resin composition constituting the adhesive layer 5. This can effectively improve the adhesion between the barrier layer 3 and the adhesive layer 5.

[0124] The polyurethane is not particularly limited, and any known polyurethane can be used. The adhesive layer 5 may be, for example, a cured product of two-component curing polyurethane.

[0125] The proportion of polyurethane in adhesive layer 5 is preferably in the range of 0.1 to 50 mass %, and more preferably in the range of 0.5 to 40 mass %, of the resin composition constituting adhesive layer 5. This effectively improves the adhesion between barrier layer 3 and adhesive layer 5 in an atmosphere containing components that induce corrosion of the barrier layer, such as an electrolyte solution.

[0126] In addition, when the adhesive layer 5 is a cured product of a resin composition containing at least one selected from the group consisting of a compound having an isocyanate group, a compound having an oxazoline group, and an epoxy resin, and the acid-modified polyolefin, the acid-modified polyolefin functions as the main agent, and the compound having an isocyanate group, the compound having an oxazoline group, and the compound having an epoxy group each function as a curing agent.

[0127] From the viewpoint of effectively suppressing crushing when the first heat-sealable resin layer 41 is heat-sealed and improving the sealing properties of the packaging material for an electricity storage device, the total thickness of the adhesive layer 5 and the heat-sealable resin layer 4 is preferably about 50 μm or more, more preferably about 60 μm or more, and even more preferably about 70 μm or more, and is preferably about 120 μm or less, more preferably about 100 μm or less, with preferred ranges including about 50 to 120 μm, about 50 to 100 μm, about 60 to 120 μm, about 60 to 100 μm, about 70 to 120 μm, and about 70 to 100 μm.

[0128] Furthermore, the preferred ratio between the thickness of the first heat-sealable resin layer 41 and the thickness of the second heat-sealable resin layer 42 is such that, when the thickness of the first heat-sealable resin layer 41 is 1.0, the thickness of the second heat-sealable resin layer 42 is preferably approximately 1.5 to 6.0, more preferably approximately 1.7 to 5.5, and even more preferably approximately 2.0 to 5.0. Furthermore, the preferred ratio of the thickness of the adhesive layer 5 to the thickness of the first heat-sealable resin layer 41 to the thickness of the second heat-sealable resin layer 42 is preferably such that, when the thickness of the first heat-sealable resin layer 41 is 1.0, the thickness of the adhesive layer 5 is approximately 0.5 to 3.0 and the thickness of the second heat-sealable resin layer 42 is approximately 1.5 to 6.0; more preferably, the thickness of the adhesive layer 5 is approximately 0.7 to 2.3 and the thickness of the second heat-sealable resin layer 42 is approximately 1.7 to 5.5; and even more preferably, the thickness of the adhesive layer 5 is approximately 1.0 to 2.0 and the thickness of the second heat-sealable resin layer 42 is approximately 2.0 to 5.0.

[0129] In addition, specific examples of preferred ratios between the thickness of the first heat-sealable resin layer 41 and the thickness of the second heat-sealable resin layer 42 include, when the thickness of the first heat-sealable resin layer 41 is 1.0, the thickness of the second heat-sealable resin layer 42 is, for example, 2.0, 2.7, 3.0, 4.0, 5.0, 6.0, etc. In addition, preferred specific examples of the thickness of the adhesive layer 5, the first heat-sealable resin layer 41, and the second heat-sealable resin layer 42 include a case where the thickness of the first heat-sealable resin layer 41 is 1.0, the thickness of the adhesive layer 5 is 1.0, and the thickness of the second heat-sealable resin layer 42 is 2.0, a case where the thickness of the adhesive layer 5 is 1.7 and the thickness of the second heat-sealable resin layer 42 is 2.7, a case where the thickness of the adhesive layer 5 is 1.3 and the thickness of the second heat-sealable resin layer 42 is 3.0, and a case where the thickness of the adhesive layer 5 is 2.0 and the thickness of the second heat-sealable resin layer 42 is 5.0.

[0130] From the viewpoint of effectively suppressing crushing when the first heat-sealable resin layer 41 is heat-sealed and improving the sealing performance of the electrical storage device packaging material, the thickness of the adhesive layer 5 may be greater than the thickness of the first heat-sealable resin layer 41. For example, when the heat-sealable resin layer 4 is composed of a single layer of the first heat-sealable resin layer 41 and the adhesive layer 5 is provided between the barrier layer 3 and the first heat-sealable resin layer 41, the thickness of the adhesive layer 5 is preferably equal to or greater than the thickness of the first heat-sealable resin layer 41. For the first heat-sealable resin layer 41, a resin that flows more easily at high temperatures than the adhesive layer 5 is preferably used so as to achieve excellent thermal adhesion. By achieving such a thickness relationship, the first heat-sealable resin layer 41, which is a part of the heat-sealable resin layer 4 and is composed of a resin that flows easily, can be made thinner, thereby improving the insulation of the electrical storage device packaging material. By appropriately adjusting the MFR, melting point, molecular weight, etc. of the resin constituting the first thermally adhesive resin layer 41, it is possible to make the first thermally adhesive resin layer 41 a resin layer that flows easily at high temperatures.

[0131] Furthermore, in the packaging material 10 for an electricity storage device according to the present disclosure, when the heat-sealable resin layer 4 includes a first heat-sealable resin layer 41 and a second heat-sealable resin layer 42, the thickness of the second heat-sealable resin layer 42 is preferably equal to or greater than the thickness of the adhesive layer 5. The second heat-sealable resin layer 42 has better moisture barrier properties than the adhesive layer 5, which contributes to adhesion, and so providing such a thickness relationship can improve the moisture barrier properties of the packaging material for an electricity storage device.

[0132] In order to achieve high insulating properties after heat-sealing of the heat-sealable resin layer, it is preferable that the thickness of the second heat-sealable resin layer 42 is greater than the thickness of the adhesive layer 5, and that the thickness of the adhesive layer 5 is greater than the thickness of the first heat-sealable resin layer 41.

[0133] The thickness of adhesive layer 5 is preferably about 60 μm or less, about 50 μm or less, about 40 μm or less, about 30 μm or less, about 20 μm or less, about 10 μm or less, about 8 μm or less, about 5 μm or less, or about 3 μm or less, and is also preferably about 0.1 μm or more, about 0.5 μm or more, about 5 μm or more, about 10 μm or more, or about 20 μm or more, and the thickness range is preferably about 0.1 to 60 μm, 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 10 μm, or about 0.1 to 8 μm. , about 0.1 to 5 μm, about 0.1 to 3 μm, about 0.5 to 60 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, about 0.5 μm to 10 μm, about 0.5 to 8 μm, about 0.5 to 5 μm, about 0.5 to 3 μm, about 5 to 60 μm, about 5 to 50 μm, about 5 to 40 μm, about 5 to 30 μm, about 5 to 20 μm, about 5 μm to 10 μm, about 5 to 8 μm, about 10 to 60 μm, about 10 to 50 μm, about 10 to 40 μm, about 10 to 30 μm, and about 10 to 20 μm. More specifically, when the adhesive layer 5 is an adhesive exemplified as the adhesive layer 2 or a cured product of an acid-modified polyolefin and a curing agent, the thickness is preferably about 1 to 10 μm, more preferably 1 μm or more but less than 10 μm, even more preferably about 1 to 8 μm, even more preferably about 1 to 5 μm, and even more preferably about 1 to 3 μm. When a resin exemplified as the first heat-sealable resin layer 41 is used, the thickness is preferably about 2 to 60 μm, about 2 to 50 μm, about 10 to 60 μm, about 10 to 50 μm, about 20 to 60 μm, or about 20 to 50 μm. When the adhesive layer 5 is an adhesive exemplified as the adhesive layer 2 or a cured product of a resin composition containing an acid-modified polyolefin and a curing agent, the adhesive layer 5 can be formed, for example, by applying the resin composition and curing it by heating or the like. When a resin exemplified as the first heat-sealable resin layer 41 is used, the adhesive layer 5 can be formed, for example, by extrusion molding the heat-sealable resin layer 4 and the adhesive layer 5.

[0134] In the packaging material 10 for an electricity storage device of the present disclosure, specific examples of preferred laminated structures on the side of the barrier layer 3 opposite to the base material layer 1 side include a laminated structure in which, from the barrier layer 3 side, an adhesive layer 5 having a thickness of about 20 to 60 μm and a first heat-sealable resin layer 41 having a thickness of 20 to 50 μm are laminated; a laminated structure in which an adhesive layer 5 having a thickness of about 20 to 60 μm and a first heat-sealable resin layer 41 having a thickness of 20 to 40 μm are laminated; a laminated structure in which an adhesive layer 5 having a thickness of about 5 to 30 μm, a second heat-sealable resin layer 42 having a thickness of about 30 to 80 μm, and a first heat-sealable resin layer 41 having a thickness of about 5 to 25 μm are laminated; and a laminated structure in which an adhesive layer 5 having a thickness of about 5 to 20 μm, a second heat-sealable resin layer 42 having a thickness of about 40 to 80 μm, and a first heat-sealable resin layer 41 having a thickness of about 5 to 25 μm are laminated.

[0135] [Surface coating layer 6] The packaging material for an electricity storage device according to the present disclosure may have a surface coating layer 6 on the substrate layer 1 (the side of the substrate layer 1 opposite to the barrier layer 3) as needed, for the purpose of improving at least one of design, electrolyte resistance, scratch resistance, formability, etc. The surface coating layer 6 is a layer located on the outermost layer side of the packaging material for an electricity storage device when an electricity storage device is assembled using the packaging material for an electricity storage device.

[0136] The surface coating layer 6 can be formed from a resin such as polyvinylidene chloride, polyester, polyurethane, acrylic resin, or epoxy resin.

[0137] When the resin forming the surface coating layer 6 is a curable resin, the resin may be either a one-component curable resin or a two-component curable resin, but is preferably a two-component curable resin. Examples of two-component curable resins include two-component curable polyurethane, two-component curable polyester, and two-component curable epoxy resin. Among these, two-component curable polyurethane is preferred.

[0138] Examples of two-component curing polyurethanes include polyurethanes containing a base agent containing a polyol compound and a curing agent containing an isocyanate compound. Preferred examples include two-component curing polyurethanes that use a polyol such as polyester polyol, polyether polyol, or acrylic polyol as the base agent and an aromatic or aliphatic polyisocyanate as the curing agent. Furthermore, it is preferable to use a polyester polyol that has hydroxyl groups on the side chain in addition to the terminal hydroxyl groups of the repeating unit as the polyol compound. Forming the surface coating layer 6 from polyurethane provides the electrical storage device exterior material with excellent electrolyte resistance.

[0139] The surface coating layer 6 may contain additives such as the aforementioned lubricants, antiblocking agents, matting agents, flame retardants, antioxidants, tackifiers, and antistatic agents, at least on the surface and / or inside of the surface coating layer 6, as needed, depending on the functionality to be imparted to the surface of the surface coating layer 6. Examples of additives include fine particles with an average particle size of approximately 0.5 nm to 5 μm. The average particle size of the additive is the median size measured with a laser diffraction / scattering particle size distribution analyzer.

[0140] The additive may be either inorganic or organic. The shape of the additive is not particularly limited, and examples thereof include spherical, fibrous, plate-like, amorphous, and scaly shapes.

[0141] Specific examples of additives include talc, silica, graphite, kaolin, montmorillonite, mica, hydrotalcite, silica gel, zeolite, aluminum hydroxide, magnesium hydroxide, zinc oxide, magnesium oxide, aluminum oxide, neodymium oxide, antimony oxide, titanium oxide, cerium oxide, calcium sulfate, barium sulfate, calcium carbonate, calcium silicate, lithium carbonate, calcium benzoate, calcium oxalate, magnesium stearate, alumina, carbon black, carbon nanotubes, high-melting-point nylon, acrylate resin, crosslinked acrylic, crosslinked styrene, crosslinked polyethylene, benzoguanamine, gold, aluminum, copper, and nickel. The additives may be used alone or in combination of two or more. Among these additives, silica, barium sulfate, and titanium oxide are preferred from the viewpoints of dispersion stability, cost, and the like. The additives may also be subjected to various surface treatments, such as insulation treatment and high-dispersibility treatment.

[0142] The method for forming the surface coating layer 6 is not particularly limited, and examples thereof include a method of applying a resin to form the surface coating layer 6. When an additive is blended into the surface coating layer 6, a resin mixed with the additive may be applied.

[0143] The thickness of the surface coating layer 6 is not particularly limited as long as the surface coating layer 6 exhibits the above-mentioned functions, and may be, for example, about 0.5 to 10 μm, and preferably about 1 to 5 μm.

[0144] 3. Manufacturing method for exterior materials for power storage devices The method for producing the electrical storage device packaging material is not particularly limited as long as it can produce a laminate in which the layers of the electrical storage device packaging material of the present invention are laminated, and examples include a method comprising a step of laminating at least a base material layer 1, a barrier layer 3, and a heat-sealable resin layer 4 in this order. In the method for producing the electrical storage device packaging material 10 of the present disclosure, the heat-sealable resin layer 4 is composed of a single layer or multiple layers, and of the heat-sealable resin layer 4, the first heat-sealable resin layer 41 that forms the surface of the laminate has a logarithmic decrement ΔE of 0.20 or less at 140°C in rigid pendulum measurement. Details of the electrical storage device packaging material 10 of the present disclosure are as described above.

[0145] An example of a method for producing an exterior packaging material for an electricity storage device of the present invention is as follows. First, a laminate (hereinafter, sometimes referred to as "laminate A") is formed in which a base layer 1, an adhesive layer 2, and a barrier layer 3 are laminated in this order. Specifically, laminate A can be formed by a dry lamination method in which an adhesive used to form adhesive layer 2 is applied to base layer 1 or to barrier layer 3 whose surface has been chemically treated as necessary, by a coating method such as gravure coating or roll coating, and then dried, and then the barrier layer 3 or base layer 1 is laminated thereon, and the adhesive layer 2 is cured.

[0146] Next, a heat-sealable resin layer 4 is laminated on the barrier layer 3 of the laminate A. When the heat-sealable resin layer 4 is laminated directly on the barrier layer 3, the heat-sealable resin layer 4 may be laminated on the barrier layer 3 of the laminate A by a method such as thermal lamination or extrusion lamination. When an adhesive layer 5 is provided between the barrier layer 3 and the heat-sealable resin layer 4, for example, (1) a method of laminating the adhesive layer 5 and the heat-sealable resin layer 4 by extruding them onto the barrier layer 3 of the laminate A (co-extrusion lamination, tandem lamination), (2) a method of separately forming a laminate in which the adhesive layer 5 and the heat-sealable resin layer 4 are laminated, and laminating this on the barrier layer 3 of the laminate A by a thermal lamination, or a method of forming a laminate in which the adhesive layer 5 is laminated on the barrier layer 3 of the laminate A, and laminating this on the heat-sealable resin layer 4 by a thermal lamination. (3) a method (sandwich lamination method) in which a molten adhesive layer 5 is poured between the barrier layer 3 of the laminate A and a heat-sealable resin layer 4 previously formed into a sheet, and the laminate A and the heat-sealable resin layer 4 are bonded together via the adhesive layer 5; (4) a method in which an adhesive for forming the adhesive layer 5 is solution-coated on the barrier layer 3 of the laminate A, followed by drying or baking, and then the heat-sealable resin layer 4 previously formed into a sheet is laminated on the adhesive layer 5.

[0147] When the surface coating layer 6 is provided, the surface coating layer 6 is laminated on the surface of the base material layer 1 opposite to the barrier layer 3. The surface coating layer 6 can be formed, for example, by applying the above-mentioned resin for forming the surface coating layer 6 to the surface of the base material layer 1. The order of the step of laminating the barrier layer 3 on the surface of the base material layer 1 and the step of laminating the surface coating layer 6 on the surface of the base material layer 1 is not particularly limited. For example, after the surface coating layer 6 is formed on the surface of the base material layer 1, the barrier layer 3 may be formed on the surface of the base material layer 1 opposite to the surface coating layer 6.

[0148] As described above, a laminate is formed which includes the optional surface coating layer 6 / substrate layer 1 / optional adhesive layer 2 / barrier layer 3 / optional adhesive layer 5 / thermally adhesive resin layer 4 in this order, and in order to strengthen the adhesion of the optional adhesive layer 2 and adhesive layer 5, the laminate may be further subjected to a heat treatment.

[0149] In the packaging material for an electricity storage device, each layer constituting the laminate may be subjected to a surface activation treatment such as corona treatment, blast treatment, oxidation treatment, ozone treatment, etc., as needed to improve processability. For example, by subjecting the surface of the base layer 1 opposite to the barrier layer 3 to corona treatment, the printability of ink on the surface of the base layer 1 can be improved.

[0150] 4. Applications of exterior materials for energy storage devices The exterior packaging material for an electricity storage device according to the present disclosure is used in a package for hermetically housing an electricity storage device element such as a positive electrode, a negative electrode, an electrolyte, etc. That is, an electricity storage device can be formed by housing an electricity storage device element including at least a positive electrode, a negative electrode, and an electrolyte in a package formed from the exterior packaging material for an electricity storage device according to the present disclosure.

[0151] Specifically, an electricity storage device using the electricity storage device packaging material is provided by covering an electricity storage device element having at least a positive electrode, a negative electrode, and an electrolyte with the electricity storage device packaging material of the present disclosure in a state in which metal terminals connected to each of the positive electrode and the negative electrode protrude outward, so that a flange portion (a region where the heat-sealable resin layers contact each other) can be formed around the periphery of the electricity storage device element, and heat-sealing the heat-sealable resin layers of the flange portion to form a hermetic seal. Note that when an electricity storage device element is housed in a package formed from the electricity storage device packaging material of the present disclosure, the package is formed so that the heat-sealable resin portion of the electricity storage device packaging material of the present disclosure faces inside (the surface in contact with the electricity storage device element).

[0152] The exterior material for an electricity storage device according to the present disclosure can be suitably used in electricity storage devices such as batteries (including condensers, capacitors, etc.). The exterior material for an electricity storage device according to the present disclosure may be used in either primary or secondary batteries, but is preferably used in secondary batteries. The type of secondary battery to which the exterior material for an electricity storage device according to the present disclosure is applied is not particularly limited, and examples include lithium ion batteries, lithium ion polymer batteries, all-solid-state batteries, lead-acid batteries, nickel-metal hydride batteries, nickel-cadmium batteries, nickel-iron batteries, nickel-zinc batteries, silver oxide-zinc batteries, metal-air batteries, polyvalent cation batteries, condensers, and capacitors. Among these secondary batteries, lithium ion batteries and lithium ion polymer batteries are suitable applications for the exterior material for an electricity storage device according to the present disclosure. [Example]

[0153] The present disclosure will be described in detail below with reference to examples and comparative examples, but the present disclosure is not limited to the examples.

[0154] <Manufacturing of exterior materials for energy storage devices> Example 1 and Comparative Example 1 A polyethylene terephthalate (PET) film (12 μm thick) and an oriented nylon (ONy) film (15 μm thick) were prepared as the substrate layer. A two-component urethane adhesive (a polyol compound and an aromatic isocyanate compound) was applied (3 μm) to the PET film to adhere it to the ONy film. Aluminum foil (JIS H4160:1994 A8021H-O (40 μm thick)) was prepared as the barrier layer. A two-component urethane adhesive (a polyol compound and an aromatic isocyanate compound) was then applied to one side of the aluminum foil to form an adhesive layer (3 μm thick) on the barrier layer. The adhesive layer on the barrier layer and the substrate layer (ONy film side) were then laminated by dry lamination, followed by aging treatment to produce a substrate layer / adhesive layer / barrier layer laminate. Both sides of the aluminum foil were chemically treated. The chemical conversion treatment of aluminum foil is carried out using a treatment solution consisting of phenolic resin, chromium fluoride compound, and phosphoric acid, with a coating amount of chromium of 10 mg / m 2 (dry mass) was applied to both sides of an aluminum foil by roll coating, and baked.

[0155] Next, maleic anhydride-modified polypropylene as an adhesive layer (20 μm thick), random polypropylene as a second heat-sealable resin layer (50 μm thick), and random polypropylene as a first heat-sealable resin layer (10 μm thick) were co-extruded onto the barrier layer of each laminate obtained above, thereby laminating the adhesive layer / second heat-sealable resin layer / first heat-sealable resin layer on the barrier layer, thereby obtaining a packaging material for an electricity storage device in which the substrate layer (30 μm thick including the adhesive) / adhesive layer (3 μm) / barrier layer (40 μm) / adhesive layer (20 μm) / second heat-sealable resin layer (50 μm) / first heat-sealable resin layer (10 μm) were laminated in this order. The first heat-sealable resin layers of Example 1 and Comparative Example 1 each had the logarithmic decrement ΔE at 140°C (values ​​measured using a rigid pendulum-type physical property tester) listed in Table 1.

[0156] Example 2 and Comparative Example 2 A polyethylene terephthalate (PET) film (12 μm thick) and an oriented nylon (ONy) film (15 μm thick) were prepared as the substrate layer. A two-component urethane adhesive (a polyol compound and an aromatic isocyanate compound) was applied (3 μm) to the PET film to adhere it to the ONy film. Aluminum foil (JIS H4160:1994 A8021H-O (40 μm thick)) was prepared as the barrier layer. A two-component urethane adhesive (a polyol compound and an aromatic isocyanate compound) was then applied to one side of the aluminum foil to form an adhesive layer (3 μm thick) on the barrier layer. The adhesive layer on the barrier layer and the substrate layer (ONy film side) were then laminated by dry lamination, followed by aging treatment to produce a substrate layer / adhesive layer / barrier layer laminate. Both sides of the aluminum foil were chemically treated. The chemical conversion treatment of aluminum foil is carried out using a treatment solution consisting of phenolic resin, chromium fluoride compound, and phosphoric acid, with a coating amount of chromium of 10 mg / m 2 (dry mass) was applied to both sides of an aluminum foil by roll coating, and baked.

[0157] Next, maleic anhydride-modified polypropylene as an adhesive layer (40 μm thick) and random polypropylene as a first heat-sealable resin layer (40 μm thick) were co-extruded onto the barrier layer of each laminate obtained above, thereby laminating the adhesive layer / first heat-sealable resin layer on the barrier layer, thereby obtaining packaging materials for electricity storage devices in which the substrate layer (30 μm thick including adhesive) / adhesive layer (3 μm) / barrier layer (40 μm) / adhesive layer (40 μm) / first heat-sealable resin layer (40 μm) were laminated in this order. The first heat-sealable resin layers of Example 2 and Comparative Example 2 each had the logarithmic decrement ΔE at 140°C (values ​​measured using a rigid pendulum-type physical property tester) shown in Table 1.

[0158] Example 3 An outer casing material for a storage battery device was obtained in the same manner as in Example 1, except that a polyethylene terephthalate (PET) film (thickness 25 μm) was used as the base layer instead of a laminate of a polyethylene terephthalate (PET) film (thickness 12 μm) and an oriented nylon (ONy) film (thickness 15 μm). The outer casing material was laminated in the following order: base layer (thickness 25 μm), adhesive layer (3 μm), barrier layer (40 μm), adhesive layer (20 μm), second heat-sealable resin layer (50 μm), and first heat-sealable resin layer (10 μm).

[0159] Example 4 An outer casing material for a storage battery device was obtained in the same manner as in Example 1, except that a stretched nylon (ONy) film (thickness 25 μm) was used as the base layer instead of a laminate of a polyethylene terephthalate (PET) film (thickness 12 μm) and a stretched nylon (ONy) film (thickness 15 μm). The outer casing material was laminated in the following order: base layer (thickness 25 μm), adhesive layer (3 μm), barrier layer (40 μm), adhesive layer (20 μm), second heat-sealable resin layer (50 μm), and first heat-sealable resin layer (10 μm).

[0160] <Measurement of the logarithmic decrement ΔE of the first heat-sealable resin layer> Each of the electrical storage device packaging materials obtained above was cut into a rectangle with a width (TD: Transverse Direction) of 15 mm and a length (MD: Machine Direction) of 45 mm to prepare a test sample (electrical storage device packaging material 10). The MD of the electrical storage device packaging material corresponds to the rolling direction (RD) of the aluminum alloy foil, and the TD of the electrical storage device packaging material corresponds to the TD of the aluminum alloy foil, and the rolling direction (RD) of the aluminum alloy foil can be determined from the rolling marks. When the MD of the electrical storage device packaging material cannot be identified from the rolling marks of the aluminum alloy foil, it can be identified by the following method. To confirm the MD of the electrical storage device packaging material, a cross section of the heat-sealable resin layer of the electrical storage device packaging material is observed with an electron microscope to confirm the sea-island structure, and the direction parallel to the cross section where the average diameter of the island shapes in the direction perpendicular to the thickness direction of the heat-sealable resin layer is greatest can be determined to be the MD. Specifically, the sea-island structure is confirmed by observing electron microscope photographs of a cross section of the heat-sealable resin layer in the longitudinal direction and cross sections at angles of 10 degrees from the direction parallel to the longitudinal cross section, up to a direction perpendicular to the longitudinal cross section (a total of 10 cross sections). Next, the shape of each individual island is observed in each cross section. For each island, the straight-line distance connecting the leftmost end in the direction perpendicular to the thickness direction of the heat-sealable resin layer to the rightmost end in the same direction is defined as the diameter y. For each cross section, the average of the diameters y of the top 20 island shapes in descending order of diameter y is calculated. The direction parallel to the cross section with the largest average diameter y of the island shape is determined as MD. Figure 6 shows a schematic diagram illustrating the method for measuring the logarithmic decrement ΔE using rigid pendulum measurements. A rigid pendulum-type physical property tester (model number: RPT-3000W, manufactured by A&D Co., Ltd.) was used, with FRB-100 for the frame of pendulum 30, RBP-060 for the cylindrical cylinder edge 30a of the edge portion, CHB-100 for the cooling block 31, a vibration displacement detector 32, and a weight 33, and the initial amplitude was set to 0.3 degrees. The test sample was placed on the cooling block 31 with the measurement surface (first heat-fusible resin layer) facing upward, and the cylindrical cylinder edge 30a with pendulum 30 attached was set on the measurement surface so that the axial direction was perpendicular to the MD direction of the test sample.To prevent the test sample from lifting or warping during measurement, tape was applied to a location on the cooling block 31 that would not affect the measurement results. The cylindrical cylinder edge 30a was brought into contact with the surface of the first heat-sealable resin layer. Next, the logarithmic decrement ΔE of the first heat-sealable resin layer was measured using the cooling block 31 at a temperature increase rate of 3°C / min over a temperature range of 30°C to 200°C. The logarithmic decrement ΔE was measured when the surface temperature of the first heat-sealable resin layer of the test sample (electrical storage device packaging material 10) reached 140°C. (Test samples that had already been measured were not used; instead, three newly cut samples were used and the average value was used.) For the first heat-sealable resin layer, each of the electrical storage device packaging materials obtained above was immersed in 15% hydrochloric acid to dissolve the base layer and aluminum foil. The test samples, which consisted of only the adhesive layer and heat-sealable resin layer, were thoroughly dried and the logarithmic decrement ΔE was measured. The logarithmic decrement ΔE at 140°C is shown in Table 1. The logarithmic decrement ΔE is calculated by the following formula. ΔE=[ln(A1 / A2)+ln(A2 / A3)+...+ln(An / An+1)] / n A: Amplitude n: wave number

[0161] The logarithmic decrement ΔE at 80° C. was measured in the same manner as in <Measurement of logarithmic decrement ΔE of first heat-sealable resin layer>, except that the logarithmic decrement ΔE was measured when the surface temperature of the first heat-sealable resin layer was 80° C. The results are shown in Table 1.

[0162] <Measurement of the remaining thickness of the first heat-sealable resin layer> Each of the resulting electrical storage device exterior materials was cut to a length of 150 mm and a width of 60 mm to prepare a test sample (electrical storage device exterior material 10). Next, the first heat-sealable resin layers of test samples prepared from the same electrical storage device exterior material were placed face-to-face. Next, in this state, a 7 mm-wide metal plate was used to heat and pressurize both sides of the test sample in the stacking direction at a temperature of 190°C, at the surface pressures (MPa) listed in Table 1, for a time of 3 seconds, to heat-seal the first heat-sealable resin layers. The heat-sealed portions of the test sample were then cut in the stacking direction using a microtome, and the thicknesses of the two first heat-sealable resin layers that were heat-sealed to each other were measured for the exposed cross sections. The test sample before heat-sealing was also cut in the stacking direction using a microtome in the same manner, and the thicknesses of the two first heat-sealable resin layers were measured for the exposed cross sections. The ratio of the total thickness of the two first heat-sealable resin layers after heat fusion to the total thickness of the two first heat-sealable resin layers before heat fusion was calculated, and the remaining ratio (%) of the total thickness of the two first heat-sealable resin layers was measured. The results are shown in Table 1.

[0163] <Observation of the cross-sectional structure of the heat-sealed part> Each electrical storage device exterior material was subjected to heat and pressure under conditions of a width of 7 mm, a temperature of 190°C, a pressure of 0.5 MPa, and 3 seconds to heat-seal the heat-sealable resin layers together, forming the heat-sealed portion. Next, the heat-sealed portion was cut in the thickness direction using a microtome, and the resulting cross section was observed under a microscope. The microscope used was a VK-9710 manufactured by Keyence Corporation. For reference, photomicrographs of the cross sections of Examples 1 and 2 and Comparative Examples 1 and 2 are shown in FIG. 7 (Example 1), FIG. 8 (Example 2), FIG. 9 (Comparative Example 1), and FIG. 10 (Comparative Example 2), respectively. The photomicrographs in FIGS. 7 to 10 indicate the positions of the base layer 1, adhesive layer 2, barrier layer 3, adhesive layer 5, first heat-sealable resin layer 41, and second heat-sealable resin layer 42, respectively.

[0164] Furthermore, the cross-sectional structure of the heat-sealed portion was evaluated based on the micrographs according to the following criteria. The results are shown in Table 1. The following evaluations of A and B indicate that collapse during heat-sealing of the first heat-sealable resin layer was effectively suppressed. A: In the heat-sealed portion, the heat-sealable resin layer does not protrude inward (toward the space in which the exterior packaging material for an electricity storage device is housed). B: In the heat-sealed portion, the heat-sealable resin layer slightly protrudes inward (toward the space in which the exterior packaging material for an electricity storage device is housed). C: In the heat-sealed portion, the heat-sealable resin layer significantly protrudes inward (toward the space in which the exterior packaging material for an electricity storage device is housed).

[0165] [Table 1]

[0166] In Table 1, DL indicates the adhesive that bonds the polyethylene terephthalate film and the stretched nylon film. In addition, in the second heat-sealable resin layer / first heat-sealable resin layer, the notation "-" indicates that the second heat-sealable resin layer is not provided.

[0167] As is clear from the results shown in Table 1, the exterior packaging material for an electricity storage device of Example 1-4 has a first heat-sealable resin layer constituting the surface with a logarithmic decrement ΔE of 0.20 or less at 140°C, which indicates that crushing of the first heat-sealable resin layer when heat-sealed is effectively suppressed.

[0168] As described above, the present disclosure provides the following aspects of the invention. Item 1. The device is composed of a laminate including at least a base layer, a barrier layer, and a heat-sealable resin layer in this order, the heat-fusible resin layer is composed of a single layer or multiple layers, An exterior material for an electricity storage device, wherein a first heat-sealable resin layer constituting the surface of the laminate among the heat-sealable resin layers has a logarithmic decrement ΔE of 0.20 or less at 140°C in a rigid pendulum measurement. Item 2. The packaging material for an electricity storage device according to Item 1, wherein the first heat-sealable resin layer has a thickness of 5 μm or more and 25 μm or less. Item 3. The packaging material for an electricity storage device according to Item 1 or 2, wherein, after the first heat-sealable resin layers of the laminate are placed opposite each other and heated and pressurized in the lamination direction under conditions of a temperature of 190°C, a surface pressure of 2.0 MPa, and a time of 3 seconds, a remaining ratio of the total thickness of the two opposed first heat-sealable resin layers is 30% or more. Item 4. The packaging material for an electricity storage device according to any one of Items 1 to 3, wherein the resin constituting the first heat-sealable resin layer contains a polyolefin skeleton. Item 5. The packaging material for an electricity storage device according to any one of Items 1 to 4, further comprising an adhesive layer between the barrier layer and the heat-sealable resin layer. Item 6. The packaging material for an electricity storage device according to Item 5, wherein the total thickness of the adhesive layer and the heat-sealable resin layer is 50 μm or more. Item 7. The packaging material for an electricity storage device according to Item 5 or 6, wherein the adhesive layer has a thickness equal to or greater than the thickness of the first heat-sealable resin layer. Item 8. The heat-sealable resin layer includes, in order from the surface side of the laminate, the first heat-sealable resin layer and the second heat-sealable resin layer, Item 8. The packaging material for an electricity storage device according to any one of items 5 to 7, wherein the second heat-sealable resin layer has a thickness equal to or greater than the thickness of the adhesive layer. Item 9. The packaging material for an electricity storage device according to any one of Items 5 to 8, wherein the second heat-sealable resin layer has a thickness greater than the thickness of the first heat-sealable resin layer. Item 10. The packaging material for an electricity storage device according to any one of Items 5 to 9, wherein the adhesive layer has a thickness of 50 μm or less. Item 11. The packaging material for an electricity storage device according to any one of Items 1 to 10, wherein a lubricant is present on the surface of the first heat-sealable resin layer. Item 12. The method includes a step of laminating at least a base layer, a barrier layer, and a heat-sealable resin layer in this order to obtain a laminate, the heat-fusible resin layer is composed of a single layer or multiple layers, A method for producing an exterior material for an electricity storage device, wherein, among the heat-sealable resin layers, a first heat-sealable resin layer constituting the surface of the laminate has a logarithmic decrement ΔE of 0.20 or less at 140°C in rigid pendulum measurement. Item 13. An electricity storage device, in which an electricity storage device element including at least a positive electrode, a negative electrode, and an electrolyte is housed in a package formed from the exterior packaging material for an electricity storage device according to any one of Items 1 to 11. [Explanation of symbols]

[0169] 1 Base material layer 2 Adhesive layer 3 Barrier layer 4 Heat-fusible resin layer 5 Adhesive layer 6 Surface coating layer 10. Exterior materials for energy storage devices 41 First heat-fusible resin layer 42 Second heat-fusible resin layer

Claims

1. The laminate is composed of at least a base layer, a barrier layer, an adhesive layer, and a heat-sealable resin layer in this order, the heat-sealable resin layer includes a first heat-sealable resin layer and a second heat-sealable resin layer, a first heat-fusible resin layer constituting a surface of the laminate among the heat-fusible resin layers has a logarithmic decrement ΔE of 0.20 or less at 140°C in a rigid pendulum measurement; In measuring the logarithmic decrement ΔE, a rigid pendulum physical property test was performed on the first heat-fusible resin layer using a commercially available rigid pendulum physical property tester under the conditions of a cylindrical cylinder edge as an edge portion pressed against the first heat-fusible resin layer, an initial amplitude of 0.3 degrees, a temperature range of 30° C. to 200° C. and a temperature rise rate of 3° C. / min. For the first heat-fusible resin layer for which the logarithmic decrement ΔE is measured, the laminate is immersed in 15% hydrochloric acid to dissolve the base material layer and the barrier layer, and the laminate of the adhesive layer and the heat-fusible resin layer is sufficiently dried to obtain a measurement target. the first heat-sealable resin layer is formed of random polypropylene, the second heat-sealable resin layer is formed of a resin containing a polyolefin skeleton, the resin forming the adhesive layer contains a polyolefin skeleton, the thickness of the first heat-sealable resin layer is 1.0, the thickness ratio of the adhesive layer is 0.5 or more and 3.0 or less, and the thickness ratio of the second heat-sealable resin layer is 1.5 or more and 6.0 or less; the thickness of the adhesive layer is equal to or greater than the thickness of the first heat-sealable resin layer; The packaging material for an electricity storage device, wherein the second heat-sealable resin layer has a thickness equal to or greater than the thickness of the adhesive layer.

2. The packaging material for an electricity storage device according to claim 1 , wherein the first heat-sealable resin layer has a thickness of 5 μm or more and 25 μm or less.

3. 3. The exterior material for an electricity storage device according to claim 1, wherein after the first heat-sealable resin layers of the laminate are placed opposite each other and heated and pressurized in the lamination direction under conditions of a temperature of 190°C, a surface pressure of 2.0 MPa, and a time of 3 seconds, a remaining ratio of a total thickness of the two opposed first heat-sealable resin layers is 30% or more.

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

5. The packaging material for an electricity storage device according to any one of claims 1 to 4, wherein two or more types of lubricants are present on at least one of the surface and the interior of the heat-sealable resin layer.

6. The packaging material for an electricity storage device according to any one of claims 1 to 5, wherein the barrier layer includes at least one of an aluminum alloy foil and a stainless steel foil.

7. The packaging material for an electricity storage device according to any one of claims 1 to 6, further comprising a surface coating layer on the opposite side of the base material layer from the barrier layer side.

8. The packaging material for an electricity storage device according to any one of claims 1 to 7, wherein the substrate layer has a thickness of more than 35 µm and not more than 50 µm.

9. The packaging material for an electricity storage device according to any one of claims 1 to 8, wherein the barrier layer has a thickness of more than 50 µm and not more than 85 µm.

10. The packaging material for an electricity storage device according to any one of claims 1 to 8, wherein the barrier layer has a thickness of more than 85 µm and not more than 200 µm.

11. The method includes a step of laminating at least a base layer, a barrier layer, an adhesive layer, and a heat-sealable resin layer in this order to obtain a laminate, the heat-sealable resin layer includes a first heat-sealable resin layer and a second heat-sealable resin layer, a first heat-fusible resin layer constituting a surface of the laminate among the heat-fusible resin layers has a logarithmic decrement ΔE of 0.20 or less at 140°C in a rigid pendulum measurement; In measuring the logarithmic decrement ΔE, a rigid pendulum physical property test was performed on the first heat-fusible resin layer using a commercially available rigid pendulum physical property tester under the conditions of a cylindrical cylinder edge as an edge portion pressed against the first heat-fusible resin layer, an initial amplitude of 0.3 degrees, a temperature range of 30° C. to 200° C. and a temperature rise rate of 3° C. / min. For the first heat-fusible resin layer for which the logarithmic decrement ΔE is measured, the laminate is immersed in 15% hydrochloric acid to dissolve the base material layer and the barrier layer, and the laminate of the adhesive layer and the heat-fusible resin layer is sufficiently dried to obtain a measurement target. the first heat-sealable resin layer is formed of random polypropylene, the second heat-sealable resin layer is formed of a resin containing a polyolefin skeleton, the resin forming the adhesive layer contains a polyolefin skeleton, the thickness of the first heat-sealable resin layer is 1.0, the thickness ratio of the adhesive layer is 0.5 or more and 3.0 or less, and the thickness ratio of the second heat-sealable resin layer is 1.5 or more and 6.0 or less; the thickness of the adhesive layer is equal to or greater than the thickness of the first heat-sealable resin layer; a thickness of the second heat-sealable resin layer that is equal to or greater than a thickness of the adhesive layer;

12. an adhesive layer is provided between the barrier layer and the heat-sealable resin layer, 12. The method for producing an exterior material for an electricity storage device according to claim 11, wherein the adhesive layer and the heat-sealable resin layer are formed by a co-extrusion lamination method, a tandem lamination method, a thermal lamination method, a sandwich lamination method, or a method of solution-coating an adhesive for forming the adhesive layer onto the barrier layer, and laminating the heat-sealable resin layer, which has been formed in advance into a sheet shape, onto the adhesive layer.

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