Outer packaging material for power storage device, outer packaging case for power storage device, and power storage device

Abstract

The invention relates to an outer packaging material for a power storage device, an outer packaging case, and a power storage device. The outer packaging material (1) for an electricity storage device includes a base material layer (2) formed of a heat-resistant resin, a sealing layer (3) as an inner layer, and a metal foil layer (4) disposed between the base material layer and the sealing layer, a protective layer (7) is laminated on a surface of the base material layer (2) opposite to the metal foil layer side, the protective layer (7) is configured to contain 40% by mass or more of a polyester resin, and the thickness of the protective layer (7) is 10-30 [mu] m. The polyester resin is formed from a polyester polyol having a number average molecular weight of 5,000-50,000 and having a hydroxyl group or a carboxyl group independently at at least both ends, and a polyfunctional isocyanate curing agent containing at least an aliphatic polyfunctional isocyanate compound. By means of this configuration, it is possible to provide an outer packaging material for power storage devices, which has excellent moldability, can ensure good printability of the surface, and also has excellent solvent resistance.

Description

[0001] This application is a divisional application of an invention patent application with an application date of November 30, 2017, application number 201711248386.8, the earliest priority date of December 28, 2016, and the invention name of "Outer packaging material for power storage device, outer packaging case for power storage device and power storage device". Technical Field

[0002] The present invention relates to an outer packaging material for an electrical storage device, such as a battery or capacitor used in portable devices such as smartphones and tablet computers, or a battery or capacitor used in hybrid vehicles, electric vehicles, wind power generation, solar power generation, or nighttime power storage, and an electrical storage device packaged with the outer packaging material.

[0003] It should be noted that, in the claims and the specification of this application, the term "polyester polyol" is used to include the following polyesters:

[0004] 1) Polyesters having hydroxyl groups at both ends of the main chain in the longitudinal direction

[0005] 2) Polyesters having carboxyl groups at both ends of the main chain in the longitudinal direction

[0006] 3) A polyester having a hydroxyl group at one terminal in the longitudinal direction of the main chain and a carboxyl group at the other terminal. Background Art

[0007] In recent years, with the thinning and lightening of mobile electronic devices such as smart phones and tablet terminals, as the outer packaging material of the storage devices such as lithium ion secondary batteries, lithium polymer secondary batteries, lithium ion capacitors (lithiumion capacitors), and electric double-layer capacitors (electric double-layer condensers) carried on them, a laminate formed by a heat-resistant resin layer (base material layer) / adhesive layer / metal foil layer / adhesive layer / thermoplastic resin layer (inner sealing layer) has gradually been used to replace the previous metal cans (see patent document 1). In addition, the situation in which the power supply of electric vehicles, large power supplies for storage purposes, capacitors, etc. are outer packaged with the laminate (outer packaging material) of the above-mentioned structure has also gradually increased. By performing embossing and deep drawing on the above-mentioned laminate, it is formed into a three-dimensional shape such as a roughly rectangular parallelepiped shape. By forming it into such a three-dimensional shape, it is possible to ensure a storage space for the main body of the storage device.

[0008] Furthermore, in order to achieve protection of the outer packaging material and improve its moldability (slidability), products have been proposed in which a matte varnish layer (protective layer) is provided on the outer surface of the substrate layer. As such a matte varnish layer, there is a description of a matte varnish obtained by adding an appropriate amount of an inorganic matting agent such as silica or kaolin to an olefin-based or alkyd-based synthetic resin, such as a cellulose-based, polyamide-based, vinyl chloride-vinyl acetate-based, modified polyolefin-based, rubber-based, acrylic-based, or urethane-based resin (see Patent Document 2).

[0009] Patent Document 1: Japanese Patent Application Laid-Open No. 2003-288865

[0010] Patent Document 2: Japanese Patent Application Laid-Open No. 2011-54563 Summary of the Invention

[0011] Problems to be solved by the invention

[0012] However, for example, when an electrolyte is injected into the battery body during the manufacturing process, the electrolyte (containing a solvent) may adhere to the outer surface (external surface) of the outer packaging material. If the outer surface of the outer packaging material has poor solvent resistance, this can lead to a poor appearance of the outer packaging material. For example, when a urethane-based resin is used to form a protective layer, the outer packaging material has good moldability, but the outer surface of the outer packaging material has poor solvent resistance (sufficient solvent resistance cannot be achieved).

[0013] In addition, when a fluorine-based resin is used to form a protective layer, the solvent resistance of the outer packaging material is good, but the adhesion of text, barcodes, etc. printed on the surface (outer surface) of the outer packaging material is insufficient, and bleeding is likely to occur during printing, resulting in poor printability.

[0014] The present invention has been made in view of the above technical background, and an object of the present invention is to provide a packaging material for a power storage device, a packaging case for a power storage device, and a power storage device that have excellent moldability, can ensure good printability of the surface, and are also excellent in solvent resistance.

[0015] Means for solving problems

[0016] To achieve the aforementioned objectives, the present invention provides the following means.

[0017] [1] An outer packaging material for an electrical storage device, characterized in that the outer packaging material for an electrical storage device comprises a base layer formed of a heat-resistant resin, a sealing layer as an inner layer, and a metal foil layer arranged between the base layer and the sealing layer, wherein the outer packaging material for an electrical storage device comprises:

[0018] A protective layer is laminated on the surface of the base material layer opposite to the metal foil layer.

[0019] The protective layer contains 40% by mass or more of a polyester resin, wherein the polyester resin is composed of a polyester polyol having a number average molecular weight of 5,000 to 50,000 and independently having a hydroxyl group or a carboxyl group at at least both ends, and a polyfunctional isocyanate curing agent containing at least an aliphatic polyfunctional isocyanate compound.

[0020] [2] The outer packaging material for a power storage device according to the above item 1, wherein the equivalent ratio [NCO] / [OH+COOH], which is the ratio of the number of moles of isocyanate groups in the polyfunctional isocyanate curing agent to the sum of the number of moles of the hydroxyl groups and the number of moles of the carboxyl groups, is 0.5 to 5.

[0021] [3] The outer packaging material for a storage battery device according to the above item 1 or 2, wherein the aliphatic polyfunctional isocyanate compound is at least one aliphatic polyfunctional isocyanate compound selected from the group consisting of an adduct of trimethylolpropane and an aliphatic diisocyanate compound, and an adduct of pentaerythritol and an aliphatic diisocyanate compound.

[0022] [4] The outer packaging material for a power storage device according to any one of the above items 1 to 3, wherein the polyester resin constituting the protective layer is a polyester resin formed from the polyester polyol, the polyfunctional isocyanate curing agent, and a trivalent or higher polyol.

[0023] [5] The outer packaging material for a power storage device according to any one of the above items 1 to 4, wherein the protective layer contains solid fine particles having an average particle size of 1 μm to 10 μm.

[0024] [6] The outer packaging material for a power storage device according to any one of the above items 1 to 5, wherein the protective layer contains a lubricant.

[0025] [7] The packaging material for a power storage device according to any one of the above items 1 to 6, wherein a colored layer is arranged between the base layer and the metal foil layer.

[0026] [8] The outer packaging material for a power storage device according to the above item 7, wherein the base layer and the colored layer are laminated and integrated via an easy-adhesion layer.

[0027] [9] An outer casing for an electrical storage device, formed from a molded body of the outer casing material for an electrical storage device according to any one of claims 1 to 8.

[0028]

[10] An electric storage device characterized by comprising:

[0029] a power storage device main body; and

[0030] An outer packaging member comprising the outer packaging material for a power storage device as described in any one of the preceding items 1 to 8 and / or the outer packaging case for a power storage device as described in the preceding item 9,

[0031] The power storage device main body is packaged by the packaging member.

[0032] Effects of the Invention

[0033] In the invention of [1], the protective layer is composed of a polyester resin containing 40% by mass or more, wherein the polyester resin is composed of a polyester polyol having a number average molecular weight of 5,000 to 50,000 and independently having a hydroxyl group or a carboxyl group at at least both ends, and a polyfunctional isocyanate curing agent containing at least an aliphatic polyfunctional isocyanate compound. Therefore, the protective layer has excellent formability and can be printed on the surface of the outer packaging material (the surface of the protective layer) in a good state, and the surface of the protective layer also has excellent solvent resistance.

[0034] In the invention of [2], since the equivalent ratio [NCO] / [OH+COOH] is in the range of 0.5 to 5, printing can be performed on the surface of the outer packaging material (the surface of the protective layer) in a better state, and the solvent resistance of the surface of the protective layer can be further improved.

[0035] In the invention of [3], the above-mentioned aliphatic polyfunctional isocyanate compound is the above-mentioned specific aliphatic polyfunctional isocyanate compound, and therefore, it can be printed on the surface of the outer packaging material (the surface of the protective layer) in a better state, and the solvent resistance of the surface of the protective layer can be further improved.

[0036] In the invention of [4], the polyester resin constituting the protective layer is a resin formed by polyester polyol, a polyfunctional isocyanate curing agent and a polyol having a valence of 3 or more. Therefore, the crosslinking density of the resin becomes higher, which can further improve the solvent resistance of the surface of the outer packaging material (the surface of the protective layer).

[0037] According to the invention of [5], the protective layer contains solid fine particles having an average particle size of 1 μm to 10 μm, and thus the formability of the outer packaging material can be further improved.

[0038] According to the invention of [6], the protective layer contains a lubricant, and therefore the sliding property of the surface of the outer packaging material (the surface of the protective layer) can be improved, thereby improving the moldability.

[0039] In the invention of [7], a colored layer is disposed between the base layer (heat-resistant resin layer) and the metal foil layer. Therefore, the color of the colored layer can be seen through the base layer (heat-resistant resin layer), thereby improving the design of the outer packaging material. Furthermore, since the colored layer is disposed on the inner side relative to the base layer, the colored layer is prevented from being scratched or peeling, thereby ensuring durability.

[0040] According to the invention of [8], the base material layer and the colored layer are laminated and integrated via the adhesive layer, and therefore, when the outer packaging material is molded, the colored layer can be sufficiently prevented from being peeled off from the base material layer.

[0041] According to the invention of [9], good printability of the surface can be ensured, and solvent resistance is also excellent, thereby being able to provide an outer casing for a power storage device that is molded in a good state.

[0042] The invention of

[10] can ensure good printability of the surface and has excellent solvent resistance, thereby providing a storage device packaged using a storage device packaging material and / or packaging case formed in a good state. BRIEF DESCRIPTION OF THE DRAWINGS

[0043] Figure 1 This is a cross-sectional view showing one embodiment of the outer packaging material for a power storage device according to the present invention.

[0044] Figure 2 This is a cross-sectional view showing one embodiment of the power storage device according to the present invention.

[0045] Figure 3 The composition is shown in the separated state before heat sealing. Figure 2 A three-dimensional diagram of the outer packaging material (flat object) of the power storage device, the main body of the power storage device and the outer packaging case (a molded body formed into a three-dimensional shape).

[0046] Description of Reference Numerals

[0047] 1…Outer packaging materials for power storage devices

[0048] 2…base material layer

[0049] 3…Sealing layer (inner layer)

[0050] 4…Metal foil layer

[0051] 5...First adhesive layer (outer adhesive layer)

[0052] 6...Second adhesive layer (inner adhesive layer)

[0053] 7…Protective layer

[0054] 8…easy bonding layer

[0055] 9…Coloring layer

[0056] 10…External packaging case for power storage device (molded body)

[0057] 15…External packaging components

[0058] 30…Electricity storage device

[0059] 31…Power storage device main body DETAILED DESCRIPTION

[0060] One embodiment of the outer packaging material 1 for a power storage device according to the present invention is shown in FIG. Figure 1 The outer packaging material 1 for a power storage device of this embodiment is suitable for use as a packaging material for lithium ion secondary battery cases, but is not particularly limited to such an application.

[0061] The outer packaging material 1 for a storage battery device comprises the following structure: a base material layer (heat-resistant resin layer) 2 is laminated and integrated on one side (upper surface) of a metal foil layer 4 via a first adhesive layer (outer adhesive layer) 5, a sealant layer (inner layer) 3 is laminated and integrated on the other side (lower surface) of the metal foil layer 4 via a second adhesive layer (inner adhesive layer) 6, and an integrated protective layer 7 is laminated on the side of the base material layer 2 opposite to the side of the metal foil layer 4 (see Figure 1 ).

[0062] In this embodiment, an easy-adhesive layer 8 is laminated on the lower surface of the base material layer (heat-resistant resin layer) 2, and a colored layer 9 is laminated on the lower surface of the easy-adhesive layer 8. The colored layer 9 and the metal foil layer 4 are bonded together via a first adhesive layer 5 (see FIG. Figure 1 ). That is, a colored layer 9 is arranged between the metal foil layer 4 and the base layer (heat-resistant resin layer) 2. In addition, in this embodiment, an easy-adhesive layer 8 is laminated on the lower surface of the base layer (heat-resistant resin layer) 2 by gravure coating, and the colored layer 9 is laminated on the lower surface of the easy-adhesive layer 8 by printing.

[0063] [Protective layer]

[0064] In the present invention, the protective layer 7 comprises 40% or more by mass of a polyester resin, which is composed of a polyester polyol having a number-average molecular weight of 5,000 to 50,000, independently having hydroxyl or carboxyl groups at at least two ends of the main chain in the longitudinal direction, and a polyfunctional isocyanate curing agent containing at least an aliphatic polyfunctional isocyanate compound. Due to this configuration, the outer packaging material 1 of the present invention exhibits excellent formability, enabling printing on the outer packaging material surface (the surface of the protective layer 7) in a good state, and the surface of the protective layer 7 also exhibits excellent solvent resistance.

[0065] As the polyester polyol, for example, from the viewpoint of further improving solvent resistance, it is preferable to use a polyester polyol obtained by mixing a polyol and a polycarboxylic acid and subjecting them to a polycondensation reaction, wherein at least two terminals have a hydroxyl group or a carboxyl group. That is, as the polyester polyol, a polycondensate of a polyol and a polycarboxylic acid is preferred. For example, by combining a polyol and a dicarboxylic acid and subjecting them to a polycondensation reaction at 210°C for 20 hours, the "polyester polyol having at least two terminals independently having a hydroxyl group or a carboxyl group" can be produced. The polyol is not particularly limited, and examples thereof include ethylene glycol, diethylene glycol, propylene glycol, dipropylene glycol, 1,6-hexanediol, neopentyl glycol, 1,4-butanediol, trimethylolpropane, glycerol, 1,9-nonanediol, and 3-methyl-1,5-pentanediol. The polycarboxylic acid is not particularly limited, and examples thereof include dicarboxylic acids such as aliphatic dicarboxylic acids and aromatic dicarboxylic acids. The aliphatic dicarboxylic acid is not particularly limited, and examples thereof include adipic acid, succinic acid, azelaic acid, suberic acid, sebacic acid, glutaric acid, maleic anhydride, itaconic anhydride, etc. The aromatic dicarboxylic acid is not particularly limited, and examples thereof include isophthalic acid, terephthalic acid, naphthalene dicarboxylic acid, tetrahydrophthalic anhydride, hexahydrophthalic anhydride, phthalic anhydride, trimellitic acid, and pyromellitic acid.

[0066] As the above-mentioned polyester polyol, a polyester polyol having a number average molecular weight (Mn) of 5000 to 50000 is used. When the number average molecular weight is less than 5000, the solvent resistance is poor, and when the solvent adheres to the outer surface of the outer packaging material, the surface of the protective layer will become turbid. On the other hand, if the number average molecular weight is greater than 50000, the viscosity increases, and the viscosity of the coating liquid increases, resulting in problems such as difficulty in coating or reduced coating properties. Among them, the number average molecular weight of the above-mentioned polyester polyol is preferably 8000 to 40000, and particularly preferably in the range of 10000 to 30000. It should be noted that the case where the coating properties (coating properties) can be sufficiently improved is when the number average molecular weight of the polyester polyol is in the range of 5000 to 45000.

[0067] The number average molecular weight of the polyester polyol is a value calculated in terms of polystyrene by gel permeation chromatography (GPC). Specifically, for example, the number average molecular weight is measured by the following method: using KF805L, KF803L, or KF802 (all manufactured by Showa Denko K.K.) as a column, at a column temperature of 40°C, using tetrahydrofuran (THF) as the eluent, at a flow rate of 0.2 mL / min, using a differential refractive index (RI) detector, and a sample concentration of 0.02% by mass, using a polystyrene of known molecular weight as a standard sample.

[0068] The aliphatic polyfunctional isocyanate compound (curing agent) is not particularly limited, and examples thereof include hexamethylene diisocyanate (HMDI), 1,4-butanediisocyanate, 1,2-propylene diisocyanate, and isophorone diisocyanate (IPDI). As described above, the aliphatic polyfunctional isocyanate compound includes both acyclic and cyclic (alicyclic) isocyanates. Modified aliphatic polyfunctional isocyanate compounds may also be used. The modified product of the aliphatic polyfunctional isocyanate compound is not particularly limited, and examples thereof include modified products of aliphatic polyfunctional isocyanate compounds obtained through polymerization reactions such as isocyanuration, polymerization, and carbodiimidation. Specifically, examples thereof include dimers, trimers, biuret, and allophanate of aliphatic polyfunctional isocyanate compounds, and polyisocyanates having a 2,4,6-oxadiazinetrione ring obtained from carbon dioxide and aliphatic polyfunctional isocyanate compound monomers.

[0069] Among them, as the above-mentioned aliphatic polyfunctional isocyanate compound, it is preferred to use at least one aliphatic polyfunctional isocyanate compound selected from the group consisting of an adduct of trimethylolpropane and an aliphatic polyfunctional isocyanate compound and an adduct of pentaerythritol and an aliphatic polyfunctional isocyanate compound, and it is particularly preferred to use at least one aliphatic polyfunctional isocyanate compound selected from the group consisting of an adduct of trimethylolpropane and an aliphatic diisocyanate compound and an adduct of pentaerythritol and an aliphatic diisocyanate compound.

[0070] It should be noted that, as the curing agent, the aliphatic polyfunctional isocyanate compound and the aromatic polyfunctional isocyanate compound may be used in combination within the scope of not hindering the effect of the present invention. The aromatic polyfunctional isocyanate compound is not particularly limited, and examples thereof include toluene diisocyanate (TDI), diphenylmethane diisocyanate (MDI), and methylene diphenyl diisocyanate.

[0071] The content of the aliphatic polyfunctional isocyanate compound in the polyfunctional isocyanate curing agent is preferably 30 to 100% by mass, more preferably 50 to 100% by mass, and particularly preferably 70 to 100% by mass.

[0072] The polyester resin constituting the protective layer 7 may be a polyester resin formed by "the polyester polyol", "the polyfunctional isocyanate curing agent containing the aliphatic polyfunctional isocyanate compound" and "the aliphatic compound having a plurality of functional groups capable of reacting with isocyanate groups in one molecule". The aliphatic compound also includes compounds formed by bonding with atoms such as oxygen, nitrogen, sulfur and chlorine. The aliphatic compound does not include the polyester polyol and the polyfunctional isocyanate compound. As the aliphatic compound, it is preferred to use an aliphatic compound having a molecular weight less than the number average molecular weight of the polyester polyol. In this case, the curing reaction proceeds rapidly, thereby improving productivity. In addition to this advantage, when manufacturing the outer packaging material, even if the manufacturing steps of first forming the protective layer and then laminating the metal foil and the sealing film (sealing layer) are adopted, the protective layer can be sufficiently prevented from adhering to the roller of the processing machine and being peeled off (polluting the surface of the roller). Among them, the molecular weight of the "aliphatic compound having a plurality of functional groups reactive with an isocyanate group in one molecule" is more preferably in the range of 60 to 9500, and particularly preferably in the range of 100 to 1000.

[0073] Regarding the above-mentioned aliphatic compound, there is no particular limitation on the functional group capable of reacting with an isocyanate group, and examples thereof include a hydroxyl group, an amino group, and a carboxyl group. Specifically, the above-mentioned "aliphatic compound having a plurality of functional groups capable of reacting with an isocyanate group in one molecule" is not particularly limited, and examples thereof include polyols, aliphatic diamines, and dicarboxylic acids. The above-mentioned polyol is an alcohol having two or more alcoholic hydroxyl groups in one molecule. As the above-mentioned polyol, there is no particular limitation on the functional group, and examples thereof include trimethylolethane, trimethylolpropane (TMP), trimethylolbutane, pentaerythritol, 1,2,6-hexanetriol, methylpentanediol, dimethylbutanediol, ethylene glycol, glycerol, carbitol, and sorbitol. Among them, it is preferred to use a polyol having a valence of three or more.

[0074] The content of the aliphatic compound in the polyester resin is preferably 1% by mass to 30% by mass, more preferably 1% by mass to 15% by mass, and particularly preferably 3% by mass to 10% by mass.

[0075] The content of the polyester resin in the protective layer 7 is preferably 40% to 99.9% by mass, more preferably 50% to 95% by mass, and particularly preferably 60% to 90% by mass.

[0076] The protective layer 7 is preferably composed of solid particles. By containing solid particles, the surface of the outer packaging material 1 for a storage device (the outer surface of the protective layer 7) can be given good sliding properties, thereby further improving the moldability of the outer packaging material 1 for a storage device. From the perspective of improving sliding properties, the gloss value of the surface (outer surface) of the protective layer 7 is preferably set to 30% or less, and more preferably set to 1% to 15%. The above-mentioned gloss value is a value measured using a gloss meter "micro-TRI-gloss-s" manufactured by BYK at a reflection angle of 60°. The above-mentioned solid particles are not particularly limited, and examples thereof include silica particles, aluminum oxide particles, kaolin particles, calcium oxide particles, calcium carbonate particles, calcium sulfate particles, barium sulfate particles, calcium silicate particles, silicone resin beads, acrylic resin beads, fluororesin beads, etc. Among these solid particles, silica particles, barium sulfate particles, and acrylic resin beads are preferably used. As the above-mentioned solid particles, solid particles with an average particle size of 1μm to 10μm are preferably used.

[0077] The content of the solid particles in the protective layer 7 is preferably set to 0.1% to 60% by mass. A content of 0.1% or more improves the slip properties during molding, while a content of 60% or less improves the coating process suitability during protective layer formation, thereby ensuring sufficient conformability of the protective layer. The content of the solid particles in the protective layer 7 is more preferably set to 5% to 45% by mass, and particularly preferably to 10% to 30% by mass.

[0078] The protective layer 7 preferably contains a lubricant. The inclusion of a lubricant imparts excellent sliding properties, thereby further improving the moldability of the power storage device packaging material 1. Examples of the lubricant include, but are not limited to, fatty acid amides, silicones, and waxes (such as polyethylene wax and fluorinated polyethylene wax).

[0079] The protective layer 7 may contain additives. The additives are not particularly limited, and examples thereof include reaction accelerators. The reaction accelerator is used to efficiently promote the reaction between the polyester polyol and the polyfunctional isocyanate compound. The reaction accelerator is not particularly limited, and examples thereof include dibutyltin diacetate, dibutyltin dilaurate, dibutyltin dimaleate, and tertiary amines (such as tributylamine and triethanolamine).

[0080] The thickness of the protective layer 7 (thickness after drying) is preferably set to 1 μm to 10 μm. To set the thickness of the protective layer 7 to such a thin range, the protective layer 7 is preferably formed as a coating film (a coating film formed by coating).

[0081] [Base material layer (heat-resistant resin layer)]

[0082] The base material layer (heat-resistant resin layer) 2 is primarily responsible for ensuring good formability as an outer packaging material. Specifically, it prevents the metal foil from breaking due to necking during molding. The heat-resistant resin constituting the base material layer 2 is preferably a heat-resistant resin that does not melt at the heat-sealing temperature used to heat-seal the outer packaging material 1. The heat-resistant resin preferably has a melting point at least 10°C higher than that of the thermoplastic resin constituting the sealant layer 3, and particularly preferably has a melting point at least 20°C higher than that of the thermoplastic resin.

[0083] The substrate layer (heat-resistant resin layer) 2 is preferably composed of a heat-resistant resin stretched film having a hot water shrinkage of 2% to 20%. By setting the hot water shrinkage to 2% or more, it is possible to sufficiently prevent the colored layer 9 from peeling off from the heat-resistant resin layer 2 during use in harsh environments such as high temperature and high humidity. In addition, by setting the hot water shrinkage to 20% or less, it is possible to sufficiently prevent the colored layer 9 of the outer packaging material 1 from peeling off from the heat-resistant resin layer 2 during forming such as deep drawing and embossing. Among them, as the heat-resistant resin stretched film, a heat-resistant resin stretched film having a hot water shrinkage of 2.5% to 10% is preferably used. Furthermore, a heat-resistant resin stretched film having a hot water shrinkage of 3.0% to 6.0% is more preferably used, and a heat-resistant resin stretched film having a hot water shrinkage of 3.5% to 5.0% is particularly preferably used.

[0084] The “hot water shrinkage” is the dimensional change rate of a test piece (10 cm×10 cm) of the heat-resistant resin stretched film 2 in the stretching direction before and after immersion in 95°C hot water for 30 minutes, and is determined by the following formula.

[0085] Hot water shrinkage (%) = {(XY) / X} × 100

[0086] X: Dimension in the stretching direction before immersion

[0087] Y: Dimension in the stretching direction after immersion treatment.

[0088] It should be noted that, in the case of a biaxially stretched film, its hot water shrinkage ratio is the average value of the dimensional changes in the two stretching directions.

[0089] The hot water shrinkage rate of the heat-resistant resin stretched film can be controlled by, for example, adjusting the heat setting temperature during the stretching process.

[0090] The heat-resistant resin stretched film 2 is not particularly limited, and examples thereof include stretched polyamide films such as stretched nylon films, stretched polyester films, and the like. Among them, as the heat-resistant resin stretched film 2, biaxially stretched polyamide films such as biaxially stretched nylon films, biaxially stretched polybutylene terephthalate (PBT) films, biaxially stretched polyethylene terephthalate (PET) films, or biaxially stretched polyethylene naphthalate (PEN) films are particularly preferably used. Furthermore, as the heat-resistant resin stretched film 2, a heat-resistant resin biaxially stretched film obtained by simultaneous biaxial stretching is preferably used. Furthermore, a heat-resistant resin biaxially stretched film having a ratio (MD / TD) of "hot water shrinkage in the M direction" to "hot water shrinkage in the T direction" in the range of 0.9 to 1.1 is preferably used. When a configuration having the ratio (MD / TD) in the range of 0.9 to 1.1 is employed, an outer packaging material 1 having particularly good formability can be obtained. It should be noted that the "M direction" refers to the "machine direction of travel," and the "T direction" refers to the "direction perpendicular to the M direction." The nylon mentioned above is not particularly limited, and examples thereof include nylon 6, nylon 6,6, and nylon MXD. The heat-resistant resin stretched film layer 2 may be formed of a single layer (a single stretched film) or a multilayer structure comprising, for example, a stretched polyester film / stretched polyamide film (e.g., a multilayer structure comprising a stretched PET film / stretched nylon film).

[0091] The heat-resistant resin stretched film layer 2 is preferably a biaxially stretched polyamide film with a shrinkage of 2-20%, a biaxially stretched polyethylene naphthalate (PEN) film with a shrinkage of 2-20%, or a biaxially stretched polyethylene terephthalate (PET) film with a shrinkage of 2-20%. This can further enhance the effectiveness of preventing the colored layer 9 from peeling off from the heat-resistant resin layer 2 during molding, sealing, and use in harsh environments such as high temperature and humidity.

[0092] The thickness of the substrate layer (heat-resistant resin layer) 2 is preferably 12 to 50 μm. When using a polyester film, the thickness is preferably 12 to 50 μm, and when using a nylon film, the thickness is preferably 15 to 50 μm. Setting the thickness above the preferred lower limit ensures sufficient strength for an outer packaging material, while setting the thickness below the preferred upper limit reduces stress during bulging and drawing, thereby further improving formability.

[0093] [Easy Adhesion Layer]

[0094] An easy-adhesive layer 8 can be laminated on the inner surface (the surface facing the metal foil layer 4) of the base layer (heat-resistant resin layer) 2. By coating the surface of the heat-resistant resin layer 2, which originally has insufficient adhesiveness, with a polar resin or the like, and then laminating the easy-adhesive layer 8, the adhesion and adhesion between the heat-resistant resin layer 2 and the colored layer 9 can be further improved. It should be noted that the inner surface of the heat-resistant resin layer 2 (the surface to which the easy-adhesive layer 8 is laminated) is preferably subjected to a corona treatment or the like before laminating the easy-adhesive layer 8 to improve wettability.

[0095] The method for forming the easy-adhesive layer 8 is not particularly limited, and for example, the following method can be used: an aqueous emulsion (aqueous emulsion) of one or more resins selected from the group consisting of epoxy resins, urethane resins, acrylate resins, methacrylate resins, polyester resins, and polyethyleneimine resins is applied to the surface of the base layer (heat-resistant resin layer) 2 and dried to form the easy-adhesive layer 8. The coating method is not particularly limited, and examples thereof include spray coating, gravure roll coating, reverse roll coating, and lip coating.

[0096] The easy-adhesion layer 8 is preferably composed of one or more resins selected from the group consisting of epoxy resins, urethane resins, acrylate resins, methacrylate resins, polyester resins, and polyethyleneimine resins. This configuration further enhances the adhesion between the heat-resistant resin layer 2 and the colored layer 9. This effectively prevents the colored layer 9 from peeling off from the heat-resistant resin layer 2 during forming of the outer packaging material by methods such as drawing and embossing, and when the outer packaging material is sealed for sealing purposes. Furthermore, even when the outer packaging material 1 is used in harsh environments such as high temperature and high humidity, this effectively prevents the colored layer 9 from peeling off from the heat-resistant resin layer 2.

[0097] Among them, the easy-adhesion layer 8 is particularly preferably formed of a urethane resin and an epoxy resin, or a (meth)acrylate resin and an epoxy resin. In this case, the adhesion between the heat-resistant resin layer 2 and the colored layer 9 can be further improved.

[0098] In the case of adopting the above-mentioned former structure, the mass ratio of the carbamate resin / epoxy resin in the easy-adhesive layer 8 is preferably in the range of 98 / 2 to 40 / 60. In this case, the adhesion between the heat-resistant resin layer 2 and the colored layer 9 can be further improved. When the content ratio of the carbamate resin is greater than the above-mentioned carbamate resin / epoxy resin content ratio (98 / 2), the degree of crosslinking is insufficient, and it is difficult to fully obtain solvent resistance and adhesion, so it is not preferred. On the other hand, when the content ratio of the carbamate resin is less than the above-mentioned carbamate resin / epoxy resin content ratio (40 / 60), the time until crosslinking is completed is too long, so it is not preferred. Among them, the mass ratio of the carbamate resin / epoxy resin in the easy-adhesive layer 8 is more preferably in the range of 90 / 10 to 50 / 50.

[0099] In addition, when the latter structure is adopted, the mass ratio of the (meth)acrylate resin / epoxy resin in the easy-adhesive layer 8 is preferably in the range of 98 / 2 to 40 / 60. In this case, the adhesion between the heat-resistant resin layer 2 and the colored layer 9 can be further improved. When the content ratio of the (meth)acrylate resin is greater than the above-mentioned (meth)acrylate resin / epoxy resin content ratio (98 / 2), the degree of crosslinking is insufficient, and it is difficult to obtain sufficient solvent resistance and adhesion, so it is not preferred. On the other hand, when the content ratio of the (meth)acrylate resin is less than the above-mentioned (meth)acrylate resin / epoxy resin content ratio (40 / 60), the time until crosslinking is completed is too long, so it is not preferred. Among them, the mass ratio of the (meth)acrylate resin / epoxy resin in the easy-adhesive layer 8 is more preferably in the range of 90 / 10 to 50 / 50.

[0100] A surfactant such as a glycol or an ethylene oxide adduct of a glycol may be added to the resin aqueous emulsion (resin-water emulsion) used to form the easy-adhesion layer 8. In this case, a sufficient defoaming effect can be obtained in the resin aqueous emulsion, thereby forming an easy-adhesion layer 8 with excellent surface smoothness. The surfactant is preferably contained in the resin aqueous emulsion in an amount of 0.01% to 2.0% by mass.

[0101] Furthermore, the resin aqueous emulsion (resin-water emulsion) used to form the easy-adhesion layer 8 preferably contains inorganic fine particles such as silica and colloidal silica, which can provide an anti-blocking effect. The inorganic fine particles are preferably added in an amount of 0.1 to 10 parts by mass per 100 parts by mass of the resin component.

[0102] The amount of the easy-adhesive layer 8 formed (solid content after drying) is preferably 0.01 g / m 2 ~0.5g / m 2 The range is 0.01g / m 2The above can fully bond the heat-resistant resin stretched film layer 2 and the colored ink layer 9, and the thickness of the film is 0.5 g / m 2 The following can reduce costs and be economical.

[0103] The content of the resin in the easy-adhesive layer (after drying) 8 is preferably 88% by mass to 99.9% by mass.

[0104] [Coloring Layer]

[0105] A configuration may be employed in which a colored layer 9 is disposed between the base material layer 2 and the metal foil layer 4. By employing such a configuration, a color (including achromatic color) or a design can be imparted to the outer surface of the outer packaging material 1.

[0106] The colored layer 9 is not particularly limited, and examples thereof include a black ink layer, a white ink layer, a gray ink layer, a red ink layer, a blue ink layer, a green ink layer, and a yellow ink layer.

[0107] The black ink layer 9 will be described. The black ink layer 10 is usually formed of a composition containing carbon black.

[0108] The black ink layer 9 preferably contains carbon black, diamine, polyol, and a curing agent, but is not particularly limited to such a structure.

[0109] The black ink layer (after drying) 9 preferably has a carbon black content of 15% to 60% by mass, and the total content of the diamine, polyol, and curing agent is preferably 40% to 85% by mass. The carbon black content is particularly preferably 20% to 50% by mass.

[0110] A carbon black content of less than 15% by mass not only leaves the metallic gloss imparted by the metal foil layer 4, resulting in a loss of substantial texture, but also tends to cause localized color unevenness during molding, which is undesirable. On the other hand, a carbon black content exceeding 60% by mass causes the black ink layer 9 to become hard and brittle, thereby reducing its adhesion to the metal foil layer 4 and potentially causing separation between the metal foil layer 4 and the black ink layer 9 during molding, which is undesirable.

[0111] The black ink layer 9 preferably contains 2 to 20 parts by mass of the curing agent per 100 parts by mass of the total amount of the carbon black, the diamine, and the polyol. If the curing agent content is less than 2 parts by mass, separation between the metal foil layer 4 and the black ink layer 9 may easily occur during molding. If the curing agent content exceeds 20 parts by mass, adhesion may occur when the wound outer packaging material 1 is unwound (unrolled), which may easily lead to transfer and adhesion problems on the outer surfaces of the heat-resistant resin layer 2 and the sealant layer (thermoplastic resin layer) 3. Therefore, this is not preferred.

[0112] As the carbon black, it is preferable to use carbon black having an average particle size of 0.2 μm to 5 μm.

[0113] The diamine is not particularly limited, and examples thereof include ethylenediamine, dimer diamine, 2-hydroxyethylethylenediamine, 2-hydroxyethylpropylenediamine, dicyclohexylmethanediamine, and 2-hydroxyethylpropylenediamine. Among these, it is preferred to use one or more diamines selected from the group consisting of ethylenediamine, dimer diamine, 2-hydroxyethylethylenediamine, 2-hydroxyethylpropylenediamine, and dicyclohexylmethanediamine.

[0114] Compared to polyols, the diamine reacts faster with the curing agent (isocyanate, etc.), enabling curing in a shorter time. That is, the diamine and the polyol react together with the curing agent to promote crosslinking and curing of the ink composition.

[0115] The polyol is not particularly limited, but it is preferable to use one or more selected from the group consisting of polyurethane polyols, polyester polyols, and polyether polyols.

[0116] The number average molecular weight of the polyol is preferably in the range of 1000 to 8000. When the number average molecular weight is 1000 or more, the adhesive strength after curing can be increased, and when the number average molecular weight is 8000 or less, the reaction rate with the curing agent can be increased.

[0117] The curing agent is not particularly limited, and examples thereof include isocyanate compounds. Examples of the isocyanate compound include aromatic, aliphatic, and alicyclic isocyanate compounds. Specific examples include toluene diisocyanate (TDI), diphenylmethane diisocyanate, hexamethylene diisocyanate (HDI), and isophorone diisocyanate.

[0118] The colored ink layer (excluding the black ink layer) 9 will be described. The colored ink layer (excluding the black ink layer) 9 preferably comprises a cured film comprising a colored ink composition comprising: a two-component curable polyester-urethane resin binder composed of a polyester resin as a base component and a polyfunctional isocyanate compound as a curing agent; and a colored pigment containing an inorganic pigment.

[0119] As the above-mentioned coloring pigment, a composition containing at least an inorganic pigment is adopted. As the above-mentioned coloring pigment, in addition to the above-mentioned inorganic pigments, for example, azo pigments, phthalocyanine pigments, condensed polycyclic pigments, etc. can be mentioned. In addition, as the above-mentioned inorganic pigment, there is no particular limitation, for example, carbon black, calcium carbonate, titanium oxide, zinc oxide, iron oxide, aluminum powder, etc. can be mentioned. As the above-mentioned inorganic pigment, it is preferred to use an inorganic pigment with an average particle size of 0.1μm to 5μm, and it is particularly preferred to use an inorganic pigment with an average particle size of 0.5μm to 2.5μm. When dispersing the above-mentioned coloring pigment, it is preferred to use a pigment disperser to disperse the coloring pigment. When dispersing the above-mentioned coloring pigment, a pigment dispersant such as a surfactant can also be used.

[0120] Preferably, at least 50% by mass of the coloring pigments are composed of the inorganic pigments. In this case, sufficient concealing power can be achieved to conceal the metal foil layer 4, thereby enabling the formation of a colored ink layer 9 having a specific hue that imparts a rich and luxurious feel. More preferably, at least 60% by mass of the coloring pigments are composed of the inorganic pigments.

[0121] The thickness of the colored layer 9 (after drying) is preferably 1 μm to 4 μm. A thickness of 1 μm or greater allows the color and gloss of the metal foil layer 4 to be sufficiently concealed without leaving a sense of transparency in the hue of the colored layer 9. Furthermore, a thickness of 4 μm or less allows the colored layer 9 to be sufficiently prevented from partially cracking during molding.

[0122] The colored layer 9 is not particularly limited, and can be formed, for example, by printing (applying) the following ink composition on the surface of the easy-adhesive layer 8 on the lower surface of the heat-resistant resin layer 2 using a gravure printing method or the like:

[0123] 1) an ink composition comprising carbon black, a diamine, a polyol, a curing agent, and an organic solvent; or

[0124] 2) An ink composition comprising: a two-component curable polyester polyurethane resin binder formed from a polyester resin as a main component and a polyfunctional isocyanate compound as a curing agent; and a coloring pigment containing an inorganic pigment.

[0125] The organic solvent is not particularly limited, and examples thereof include toluene.

[0126] The method for forming the colored layer 9 is not particularly limited, and examples thereof include gravure printing, reverse roll coating, and lip coating.

[0127] [Seal layer (inner layer)]

[0128] The sealant layer (inner layer) 3 is formed of a thermoplastic resin layer. It not only has excellent chemical resistance to highly corrosive electrolytes used in lithium-ion secondary batteries, but also serves to impart heat-sealability to the outer packaging material 1.

[0129] The thermoplastic resin layer 3 is not particularly limited, but is preferably an unstretched thermoplastic resin film layer. The unstretched thermoplastic resin film layer 3 is not particularly limited, but is preferably composed of an unstretched film made of at least one thermoplastic resin selected from the group consisting of polyethylene, polypropylene, olefin copolymers, acid-modified products thereof, and ionomers.

[0130] Among them, the thermoplastic resin layer 3 is more preferably a three-layer structure in which a random copolymer layer containing propylene and a copolymer component other than propylene is laminated on both sides of an intermediate layer containing an elastomer-modified olefin resin, from the viewpoint of being able to sufficiently ensure insulation during heat sealing.

[0131] The elastomer-modified olefin resin (polypropylene block copolymer) constituting the above-mentioned intermediate layer is preferably formed from elastomer-modified homopolypropylene or / and elastomer-modified random copolymer. The above-mentioned elastomer-modified random copolymer is an elastomer-modified random copolymer containing "propylene" and "other copolymer components other than propylene" as copolymer components. As the above-mentioned "other copolymer components other than propylene", there are no particular restrictions, and examples thereof include olefin components such as ethylene, 1-butene, 1-hexene, 1-pentene, and 4-methyl-1-pentene. In addition, butadiene and the like can also be mentioned. As the above-mentioned elastomer, there are no particular restrictions, and olefin-based thermoplastic elastomers are preferably used. As the above-mentioned olefin-based thermoplastic elastomer, there are no particular restrictions, and examples thereof include EPR (ethylene-propylene rubber), propylene-butene elastomer, propylene-butene-ethylene elastomer, EPDM (ethylene-propylene-diene rubber), etc., among which EPR (ethylene-propylene rubber) is preferably used. Regarding the elastomer-modified olefinic resin, the "elastomer-modified" form may be a product obtained by graft polymerization of an elastomer, a product obtained by adding an elastomer to an olefinic resin (homopolypropylene or / and the random copolymer described above), or other modified forms.

[0132] The random copolymer (layer) is a random copolymer containing "propylene" and "other copolymer components other than propylene" as copolymer components. Regarding the random copolymer, the "other copolymer components other than propylene" are not particularly limited, but examples thereof include olefin components such as ethylene, 1-butene, 1-hexene, 1-pentene, and 4-methyl-1-pentene, as well as butadiene.

[0133] The thickness of the thermoplastic resin layer 3 is preferably set to 20 μm to 80 μm. Setting it to 20 μm or greater effectively prevents the formation of pinholes, while setting it to 80 μm or less reduces the amount of resin used, thereby reducing costs. It is particularly preferred that the thickness of the thermoplastic resin layer 3 be set to 30 μm to 50 μm. The thermoplastic resin layer 3 may be a single layer or multiple layers.

[0134] [Metal foil layer]

[0135] The metal foil layer 4 is responsible for imparting gas barrier properties to the outer packaging material 1 (preventing the intrusion of oxygen and moisture). The metal foil layer 4 is not particularly limited, and examples thereof include aluminum foil, copper foil, nickel foil, stainless steel foil, and aluminum foil is generally used. Aluminum foil is preferably A8079H-O or A8021H-O as specified in JIS H4160-2006. The thickness of the metal foil layer 4 is preferably 20 μm to 100 μm. By being 20 μm or more, pinholes can be prevented from being generated during rolling when the metal foil is manufactured, and by being 100 μm or less, stress during embossing and drawing can be reduced, thereby improving formability.

[0136] The metal foil layer 4 is preferably subjected to a chemical conversion treatment on at least the inner surface 4a (the surface facing the inner adhesive layer 6). This chemical conversion treatment effectively prevents corrosion of the metal foil surface caused by contents (e.g., battery electrolyte, food, pharmaceuticals, etc.). For example, the metal foil can be subjected to a chemical conversion treatment by applying any of the following aqueous solutions 1) to 3) to the surface of the degreased metal foil and then drying the solution.

[0137] 1) An aqueous solution containing a mixture of phosphoric acid, chromic acid, and a metal salt of fluoride;

[0138] 2) an aqueous solution containing a mixture of phosphoric acid, chromic acid, a metal fluoride salt, and a non-metal fluoride salt;

[0139] 3) An aqueous solution containing a mixture of an acrylic resin or / and a phenolic resin, phosphoric acid, chromic acid, and a fluoride metal salt.

[0140] [Outer Adhesive Layer (First Adhesive Layer)]

[0141] The outer adhesive layer 5 is not particularly limited, and examples thereof include an adhesive layer formed by a two-component curing adhesive. The two-component curing adhesive is not particularly limited, and examples thereof include a two-component curing urethane adhesive, a two-component curing polyester polyurethane adhesive, etc. The two-component curing urethane adhesive is not particularly limited, and examples thereof include a two-component curing urethane adhesive containing a polyol component and an isocyanate component. This two-component curing urethane adhesive is particularly suitable for use when bonding by a dry lamination method. The polyol component is not particularly limited, and examples thereof include polyester polyol, polyether polyol, etc. The isocyanate component is not particularly limited, and examples thereof include diisocyanates such as TDI (toluene diisocyanate), HMDI (1,6-hexamethylene diisocyanate), and MDI (methylenebis(4,1-phenylene) diisocyanate). The thickness of the outer adhesive layer 5 is preferably set to 2 μm to 5 μm, and particularly preferably set to 3 μm to 4 μm. It should be noted that inorganic or organic anti-blocking agents or amide-based slip agents may be added to the outer adhesive layer 5 .

[0142] The outer adhesive layer 5 is formed, for example, by applying an adhesive such as the two-component curable adhesive described above to the upper surface of the metal foil layer 4 and / or the lower surface of the colored layer 9 laminated on the lower surface of the heat-resistant resin layer 2 via the easy-adhesion layer 8 using a gravure coating method or the like. The method for forming the outer adhesive layer 5 is merely an example and is not particularly limited to this method.

[0143] [Inner Adhesive Layer (Second Adhesive Layer)]

[0144] In order to prevent the lamination strength from deteriorating over time due to the influence of electrolytes and the like, the inner adhesive layer 5, which bonds the metal foil layer 4 to the sealant layer 3, can be made of an adhesive resin having good adhesion to at least both the metal foil layer 4 and the sealant layer 3. The specific type of resin is not particularly limited, and examples thereof include resins obtained by graft-addition modification or copolymerization of polypropylene with dicarboxylic acids such as maleic acid, fumaric acid, itaconic acid, and mesaconic acid; dicarboxylic anhydrides such as maleic anhydride, fumaric anhydride, itaconic anhydride, and mesaconic anhydride; and carboxyl group-containing monomers such as acrylic acid, methacrylic acid, crotonic acid, and itaconic acid. Among these, resins obtained by graft-addition modification with maleic anhydride, acrylic acid, or methacrylic acid are preferred, with maleic anhydride-modified polyolefin resins being particularly preferred. The method for producing the above-mentioned resin is not particularly limited, and examples thereof include a solution method in which polypropylene is dissolved in an organic solvent and reacted with an acid (such as maleic anhydride) in the presence of a free radical initiator; a melt method in which polypropylene is heated and melted and reacted with an acid (such as maleic anhydride) in the presence of a free radical initiator, and the like.

[0145] Furthermore, from the perspective of ensuring sufficient electrolyte resistance and thereby extending the lifespan of the outer packaging material, the inner adhesive layer 6 is particularly preferably composed of an adhesive composition comprising a polyolefin resin having carboxyl groups in its chemical structure and a polyfunctional isocyanate compound. This inner adhesive layer 6 can be formed, for example, by applying an adhesive solution comprising a polyolefin resin having carboxyl groups, a polyfunctional isocyanate compound, and an organic solvent to the metal foil layer 4 and / or the sealant layer 3, followed by drying.

[0146] The above-mentioned polyolefin resin having a carboxyl group (hereinafter sometimes referred to as "polyolefin resin containing a carboxyl group") is not particularly limited, and examples thereof include modified polyolefin resins obtained by graft polymerization of ethylenically unsaturated carboxylic acids or their anhydrides with polyolefins, and copolymer resins formed by olefin monomers and ethylenically unsaturated carboxylic acids. The above-mentioned polyolefin is not particularly limited, and examples thereof include homopolymers of olefin monomers such as ethylene, propylene, and butene, or copolymers of these olefin monomers. The above-mentioned ethylenically unsaturated carboxylic acids are not particularly limited, and examples thereof include acrylic acid, methacrylic acid, maleic acid, fumaric acid, crotonic acid, itaconic acid, etc. These ethylenically unsaturated carboxylic acids may be used alone or in combination of two or more. In addition, as the above-mentioned polyolefin resin containing a carboxyl group, it is preferred to use a polyolefin resin dissolved in an organic solvent.

[0147] Among them, as the above-mentioned polyolefin resin containing a carboxyl group, it is preferred to use a modified polyolefin resin obtained by graft polymerization of an ethylenically unsaturated carboxylic acid or its anhydride with a homopolymer of propylene or a copolymer of propylene and ethylene. It should be noted that the above-mentioned polyolefin resin containing a carboxyl group may be a single composition or a mixture of two or more compositions having different melting points.

[0148] The above-mentioned polyfunctional isocyanate compound acts as a curing agent that reacts with the above-mentioned polyolefin resin containing a carboxyl group to cure the adhesive composition. As the polyfunctional isocyanate compound, there is no particular limitation, and examples include toluene diisocyanate, diphenylmethane diisocyanate, 1,6-hexamethylene diisocyanate, isophorone diisocyanate, or isocyanurate-modified products of these diisocyanate compounds, biuret-modified products, or modified products obtained by addition-modifying the above-mentioned diisocyanate compounds with polyols such as trimethylolpropane. The above-mentioned polyfunctional isocyanate compound can be used alone or in combination of two or more. In addition, as the above-mentioned polyfunctional isocyanate compound, it is preferred to use a polyfunctional isocyanate compound that is soluble in an organic solvent.

[0149] As the above-mentioned organic solvent, as long as it can dissolve the above-mentioned polyolefin resin containing carboxyl or disperse it, there is no particular limitation. Among them, it is preferred to use an organic solvent that can dissolve the above-mentioned polyolefin resin containing carboxyl. In addition, as the above-mentioned organic solvent, it is preferred to use an organic solvent that is easy to volatilize the organic solvent from the above-mentioned adhesive solution by heating, etc. and remove it. As the organic solvent that can dissolve the above-mentioned polyolefin resin containing carboxyl and easily volatilize it by heating, etc. and remove it, there is no particular limitation, and examples include aromatic organic solvents such as toluene and xylene, aliphatic organic solvents such as n-hexane, alicyclic organic solvents such as cyclohexane and methylcyclohexane (MCH), ketone organic solvents such as methyl ethyl ketone (MEK), etc. These organic solvents can be used only one kind, or two or more kinds can be used in combination.

[0150] In the adhesive liquid and adhesive resin composition, the equivalent ratio [NCO] / [OH] of the isocyanate groups of the polyfunctional isocyanate compound to the hydroxyl groups constituting the carboxyl groups of the carboxyl-containing polyolefin resin is preferably set to 0.5 to 10.0. This range allows for an adhesive composition with excellent initial adhesive properties and effectively suppresses the degradation of the bond strength between the metal foil layer 4 and the sealant layer 3 caused by the battery's electrolyte over time, thereby further improving electrolyte resistance. The equivalent ratio [NCO] / [OH] is more preferably set to 1.0 to 9.0, with a range of 1.0 to 6.0 being particularly preferred.

[0151] The adhesive liquid or the adhesive composition may contain additives such as a reaction accelerator, a tackifier, and a plasticizer as needed.

[0152] The thickness of the inner adhesive layer 6 is preferably set to 1 μm to 10 μm. A thickness of 1 μm or more can provide sufficient adhesive strength, while a thickness of 10 μm or less can improve water vapor barrier properties.

[0153] In the above embodiment, the easy-adhesive layer 8 , the colored layer 9 , the first adhesive layer 5 , and the second adhesive layer 6 are provided. However, these layers are not essential constituent layers and may be omitted.

[0154] By forming the outer packaging material 1 for an electrical storage device of the present invention (such as by drawing or embossing), an outer packaging case 10 for an electrical storage device can be obtained (see Figure 3 It should be noted that the outer packaging material 1 of the present invention can also be used directly without being formed (see Figure 3 ).

[0155] An embodiment of a power storage device 30 constructed using the outer packaging material 1 of the present invention is shown in FIG. Figure 2 The power storage device 30 is a lithium ion secondary battery. Figure 2 、 3 As shown, the outer packaging component 15 is composed of an outer packaging shell 10 obtained by molding the outer packaging material 1, and a flat outer packaging material 1 that is not provided for molding. Then, the main body of the storage device (electrochemical element, etc.) 31 of a roughly rectangular parallelepiped shape is accommodated in the storage recess of the outer packaging shell 10 obtained by molding the outer packaging material 1 of the present invention, and the outer packaging material 1 of the present invention is not molded but is arranged above the main body 31 of the storage device in a manner such that its inner layer 3 side is the inner side (lower side), and the peripheral edge portion of the inner layer 3 of the flat outer packaging material 1 is sealed and joined to the inner layer 3 of the flange portion (sealing peripheral portion) 29 of the outer packaging shell 10 by heat sealing, thereby forming the storage device 30 of the present invention (see Figure 2 、 3 It should be noted that the inner surface of the storage recess of the outer packaging shell 10 becomes the inner layer (sealing layer) 3, and the outer surface of the storage recess becomes the protective layer 7 (see Figure 3 ).

[0156] Figure 239 is a heat-sealed portion formed by joining (welding) the peripheral edge of the outer packaging material 1 to the flange (sealing peripheral edge) 29 of the outer packaging case 10. It should be noted that in the above-mentioned power storage device 30, the tip of the tab connected to the power storage device body 31 is led out of the outer packaging member 15 and is omitted in the figure.

[0157] The power storage device main body 31 is not particularly limited, and examples thereof include a battery main body, a capacitor main body, and a capacitor main body.

[0158] The width of the heat-sealed portion 39 is preferably set to 0.5 mm or more. By setting the width to 0.5 mm or more, reliable sealing can be achieved. The width of the heat-sealed portion 39 is preferably set to 3 mm to 15 mm.

[0159] In the above embodiment, the outer packaging member 15 is formed of the outer packaging case 10 obtained by molding the outer packaging material 1 and the planar outer packaging material 1 (see Figure 2 、 3 ), but is not particularly limited to such a combination. For example, the outer packaging component 15 can be formed by a pair of outer packaging materials 1, or can be formed by a pair of outer packaging shells 10.

[0160] Example

[0161] Next, specific examples of the present invention will be described, but the present invention is not particularly limited to these examples.

[0162] <Example 1>

[0163] 50 parts by mass of carbon black with an average particle size of 0.8 μm, 5 parts by mass of ethylenediamine, and 45 parts by mass of a polyester polyol (number average molecular weight: 2500) were mixed to obtain a base resin. To 100 parts by mass of the base resin, 3 parts by mass of toluene diisocyanate (TDI) as a curing agent and 50 parts by mass of toluene were added, and the mixture was thoroughly stirred to obtain an ink composition.

[0164] In addition, 70 parts by mass of "TAKELAC W-6010" manufactured by Mitsui Chemicals, Inc. as a water-based urethane resin, 30 parts by mass of "Denacol EX-521" manufactured by Nagase ChemteX Corporation as a water-based epoxy resin, and 5 parts by mass of colloidal silica "SNOWTEX ST-C" (average particle size of 10 nm to 20 nm) manufactured by Nissan Chemical Industries, Ltd. as an anti-blocking agent were added and diluted with ion-exchanged water to obtain an adhesive composition for forming an easy-adhesion layer having a non-volatile matter content of 2 mass%.

[0165] Next, the adhesive composition for forming an easy-adhesive layer was applied to one side of a biaxially stretched nylon (nylon 6) film (heat-resistant resin stretched film layer, MD / TD=0.95) 2 having a thickness of 15 μm and a hot water shrinkage of 4.0% obtained by simultaneous biaxial stretching by gravure roll coating and dried. The adhesive composition was then allowed to stand at 40°C for 1 day to undergo a curing reaction, thereby forming a 0.1 g / m2 adhesive layer. 2 The easy-adhesive layer 8.

[0166] Next, the above-mentioned ink composition is printed (applied) on the surface of the easy-adhesive layer 8 of the above-mentioned biaxially stretched nylon film 2 by gravure printing, and then placed in an environment of 40°C for 1 day, thereby causing a cross-linking reaction to occur while drying to form a colored layer (black ink layer) 9 with a thickness of 3 μm, thereby obtaining a first laminate.

[0167] Furthermore, the following protective layer-forming composition was applied to the biaxially stretched nylon film 2 (unlaminated surface) of the first laminate and then allowed to stand at 60°C for 3 days to react, thereby forming a protective layer 7 having a thickness of 2 μm, thereby obtaining a second laminate. The protective layer-forming composition comprised 55 parts by mass of a polyester having hydroxyl groups at both ends of the main chain in the longitudinal direction (number average molecular weight: 5300), 13 parts by mass of an adduct of trimethylolpropane and hexamethylene diisocyanate (referred to as "Adduct A" in the table), 2 parts by mass of powdered silica having an average particle size of 2 μm, 20 parts by mass of barium sulfate having an average particle size of 2 μm, 5 parts by mass of acrylic resin beads having an average particle size of 7 μm, 5 parts by mass of polyethylene wax, and 100 parts by mass of a solvent (50 parts by mass of methyl ethyl ketone: 50 parts by mass of toluene). The protective layer-forming composition had an equivalent ratio [NCO] / [OH+COOH] of 2.9.

[0168] On the other hand, a chemical conversion treatment solution containing polyacrylic acid, phosphoric acid, trivalent chromium compound, water, and alcohol was applied to both sides of an aluminum foil 4 having a thickness of 35 μm and dried at 180°C to obtain a chromium deposition amount of 5 mg / m 2 .

[0169] Next, the second laminate was laminated on one side of the aluminum foil 4 that had undergone the chemical conversion treatment via a polyester-based polyurethane adhesive 5, with its colored layer (black ink layer) 9 side being adhered thereto. Furthermore, a 30 μm thick unstretched polypropylene film (thermoplastic resin layer) 3 was adhered to the other side of the aluminum foil 4 via a maleic anhydride-modified polypropylene adhesive 6. The laminate was then left to stand at 40°C for 5 days, thereby obtaining a laminated product. Figure 1 An outer packaging material 1 for an electricity storage device is shown.

[0170] <Example 2>

[0171] In the above protective layer-forming composition, the following procedures were repeated except that “55 parts by mass of a polyester having hydroxyl groups at both ends of the main chain in the longitudinal direction (number average molecular weight: 5300) and 13 parts by mass of an adduct of trimethylolpropane and hexamethylene diisocyanate” was replaced with “63 parts by mass of a polyester having hydroxyl groups at both ends of the main chain in the longitudinal direction (number average molecular weight: 9800) and 5 parts by mass of an adduct of trimethylolpropane and hexamethylene diisocyanate”, and that a protective layer-forming composition having an equivalent ratio [NCO] / [OH+COOH] of 1.8 was used to obtain a Figure 1 An outer packaging material 1 for an electricity storage device is shown.

[0172] <Example 3>

[0173] The protective layer-forming composition of Example 2 was further prepared by the same procedure as in Example 2 except that erucamide was further contained at a concentration of 5000 ppm and the resulting composition was used as the protective layer-forming composition. Figure 1 An outer packaging material 1 for an electricity storage device is shown.

[0174] <Example 4>

[0175] In the protective layer-forming composition, the “adduct of 55 parts by mass of a polyester having hydroxyl groups at both ends of the main chain in the longitudinal direction (number average molecular weight: 5300) and 13 parts by mass of trimethylolpropane and hexamethylene diisocyanate” was changed to “adduct of 65 parts by mass of a polyester having hydroxyl groups at both ends of the main chain in the longitudinal direction (number average molecular weight: 14500) and 3 parts by mass of trimethylolpropane and hexamethylene diisocyanate”, and a protective layer-forming composition having an equivalent ratio [NCO] / [OH+COOH] of 1.6 was used. The same procedures as in Example 1 were performed to obtain Figure 1 An outer packaging material 1 for an electricity storage device is shown.

[0176] <Example 5>

[0177] The protective layer-forming composition was prepared in the same manner as in Example 4 except that "3 parts by mass of the adduct of trimethylolpropane and hexamethylene diisocyanate" was replaced with "1.5 parts by mass of the adduct of trimethylolpropane and hexamethylene diisocyanate and 1.5 parts by mass of the adduct of trimethylolpropane and toluene diisocyanate (TDI)". Figure 1 An outer packaging material 1 for an electricity storage device is shown.

[0178] <Example 6>

[0179] In the protective layer-forming composition, the following procedures were repeated except that “55 parts by mass of a polyester having hydroxyl groups at both ends of the main chain in the longitudinal direction (number average molecular weight: 5300) and 13 parts by mass of an adduct of trimethylolpropane and hexamethylene diisocyanate” was replaced with “65 parts by mass of a polyester having hydroxyl groups at both ends of the main chain in the longitudinal direction (number average molecular weight: 14500) and 3 parts by mass of an adduct of pentaerythritol and hexamethylene diisocyanate”, and that a protective layer-forming composition having an equivalent ratio [NCO] / [OH+COOH] of 1.7 was used to obtain a Figure 1 An outer packaging material 1 for an electricity storage device is shown.

[0180] <Example 7>

[0181] The same procedure as in Example 4 was repeated except that a polyester having hydroxyl groups at both ends of the main chain in the longitudinal direction (number average molecular weight: 19600) was used instead of the polyester having hydroxyl groups at both ends of the main chain in the longitudinal direction (number average molecular weight: 14500). Figure 1 An outer packaging material 1 for an electricity storage device is shown.

[0182] <Example 8>

[0183] The same procedure as in Example 4 was repeated except that a polyester having hydroxyl groups at both ends of the main chain in the longitudinal direction (number average molecular weight: 28500) was used instead of the polyester having hydroxyl groups at both ends of the main chain in the longitudinal direction (number average molecular weight: 14500). Figure 1 An outer packaging material 1 for an electricity storage device is shown.

[0184] <Example 9>

[0185] The same procedure as in Example 1 was repeated except that a polyester having hydroxyl groups at both ends of the main chain in the longitudinal direction (number average molecular weight: 49000) was used instead of the polyester having hydroxyl groups at both ends of the main chain in the longitudinal direction (number average molecular weight: 5300). Figure 1 An outer packaging material 1 for an electricity storage device is shown.

[0186] <Example 10>

[0187] The same procedure as in Example 3 was repeated except that a polyester (number average molecular weight: 9800) having carboxyl groups at both ends of the main chain in the longitudinal direction was used instead of the polyester (number average molecular weight: 9800) having hydroxyl groups at both ends of the main chain in the longitudinal direction to obtain Figure 1 An outer packaging material 1 for an electricity storage device is shown.

[0188] <Example 11>

[0189] A protective layer-forming composition was obtained in the same manner as in Example 2 except that a protective layer-forming composition comprising 57 parts by mass of a polyester having hydroxyl groups at both ends of the main chain in the longitudinal direction (number average molecular weight: 9800), 10 parts by mass of an adduct of trimethylolpropane and hexamethylene diisocyanate, 1 part by mass of trimethylolpropane (polyol), 2 parts by mass of powdered silica having an average particle size of 2 μm, 20 parts by mass of barium sulfate having an average particle size of 2 μm, 5 parts by mass of acrylic resin beads having an average particle size of 7 μm, and 5 parts by mass of wax was used. Figure 1 An outer packaging material 1 for an electricity storage device is shown.

[0190] <Example 12>

[0191] As a protective layer-forming composition, a protective layer was obtained in the same manner as in Example 2 except that a protective layer-forming composition comprising 57 parts by mass of a polyester having hydroxyl groups at both ends of the main chain in the longitudinal direction (number average molecular weight: 9800), 10 parts by mass of an adduct of trimethylolpropane and hexamethylene diisocyanate, 1 part by mass of pentaerythritol (polyol), 2 parts by mass of powdered silica having an average particle size of 2 μm, 20 parts by mass of barium sulfate having an average particle size of 2 μm, 5 parts by mass of acrylic resin beads having an average particle size of 7 μm, and 5 parts by mass of wax was used. Figure 1 An outer packaging material 1 for an electricity storage device is shown.

[0192] <Example 13>

[0193] As a protective layer-forming composition, a protective layer was obtained in the same manner as in Example 2 except that a protective layer-forming composition comprising 57 parts by mass of a polyester having hydroxyl groups at both ends of the main chain in the longitudinal direction (number average molecular weight: 9800), 10 parts by mass of an adduct of trimethylolpropane and hexamethylene diisocyanate, 1 part by mass of glycerol (polyol), 2 parts by mass of powdered silica having an average particle size of 2 μm, 20 parts by mass of barium sulfate having an average particle size of 2 μm, 5 parts by mass of acrylic resin beads having an average particle size of 7 μm, and 5 parts by mass of wax was used. Figure 1 An outer packaging material 1 for an electricity storage device is shown.

[0194] <Example 14>

[0195] In the protective layer-forming composition, the following procedures were repeated except that “55 parts by mass of a polyester having hydroxyl groups at both ends of the main chain in the longitudinal direction (number average molecular weight: 5300) and 13 parts by mass of an adduct of trimethylolpropane and hexamethylene diisocyanate” were replaced with “65 parts by mass of a polyester having four hydroxyl groups (having hydroxyl groups at both ends of the main chain in the longitudinal direction and having two hydroxyl groups in the middle of the main chain) (number average molecular weight: 14200) and 3 parts by mass of an adduct of trimethylolpropane and hexamethylene diisocyanate” and that a protective layer-forming composition having an equivalent ratio [NCO] / [OH+COOH] of 0.8 was used to obtain Figure 1 An outer packaging material 1 for an electricity storage device is shown.

[0196] <Example 15>

[0197] In the protective layer-forming composition, the following procedures were repeated except that “55 parts by mass of a polyester having hydroxyl groups at both ends of the main chain in the longitudinal direction (number average molecular weight: 5300) and 13 parts by mass of an adduct of trimethylolpropane and hexamethylene diisocyanate” was replaced with “65 parts by mass of a polyester having four hydroxyl groups (having hydroxyl groups at both ends of the main chain in the longitudinal direction and having two hydroxyl groups in the middle of the main chain) (number average molecular weight: 11200) and 3 parts by mass of an adduct of trimethylolpropane and hexamethylene diisocyanate” and that a protective layer-forming composition having an equivalent ratio [NCO] / [OH+COOH] of 0.9 was used to obtain a Figure 1 An outer packaging material 1 for an electricity storage device is shown.

[0198] Comparative Example 1

[0199] A protective layer-forming composition comprising 65 parts by mass of a fluorinated polyol (number average molecular weight: 15,000), 3 parts by mass of an adduct of trimethylolpropane and hexamethylene diisocyanate, 2 parts by mass of powdered silica having an average particle size of 2 μm, 20 parts by mass of barium sulfate having an average particle size of 2 μm, 5 parts by mass of acrylic resin beads having an average particle size of 7 μm, and 5 parts by mass of wax was obtained in the same manner as in Example 1 except that the composition was used. Figure 1 An outer packaging material 1 for an electricity storage device is shown.

[0200] Comparative Example 2

[0201] A protective layer-forming composition comprising 53 parts by mass of a polyurethane polyol (number average molecular weight: 5400), 15 parts by mass of an adduct of trimethylolpropane and hexamethylene diisocyanate, 2 parts by mass of powdered silica having an average particle size of 2 μm, 20 parts by mass of barium sulfate having an average particle size of 2 μm, 5 parts by mass of acrylic resin beads having an average particle size of 7 μm, and 5 parts by mass of wax was obtained in the same manner as in Example 1 except that the composition was used. Figure 1 An outer packaging material 1 for an electricity storage device is shown.

[0202] Comparative Example 3

[0203] A protective layer-forming composition comprising 53 parts by mass of an acrylic polyol (number average molecular weight: 3400), 15 parts by mass of an adduct of trimethylolpropane and hexamethylene diisocyanate, 2 parts by mass of powdered silica having an average particle size of 2 μm, 20 parts by mass of barium sulfate having an average particle size of 2 μm, 5 parts by mass of acrylic resin beads having an average particle size of 7 μm, and 5 parts by mass of wax was obtained in the same manner as in Example 1 except that the composition was used. Figure 1 An outer packaging material 1 for an electricity storage device is shown.

[0204] Comparative Example 4

[0205] In the protective layer-forming composition, the following procedures were repeated except that “55 parts by mass of a polyester having hydroxyl groups at both ends of the main chain in the longitudinal direction (number average molecular weight: 5300) and 13 parts by mass of an adduct of trimethylolpropane and hexamethylene diisocyanate” was replaced with “53 parts by mass of a polyester having hydroxyl groups at both ends of the main chain in the longitudinal direction (number average molecular weight: 3900) and 15 parts by mass of an adduct of pentaerythritol and hexamethylene diisocyanate”, and that a protective layer-forming composition having an equivalent ratio [NCO] / [OH+COOH] of 2.6 was used to obtain a Figure 1 An outer packaging material 1 for an electricity storage device is shown.

[0206] <Comparative Example 5>

[0207] In the protective layer forming composition, the same procedures as in Example 1 were carried out except that "13 parts by mass of an adduct of trimethylolpropane and hexamethylene diisocyanate" was replaced with "13 parts by mass of an adduct of trimethylolpropane and toluene diisocyanate (TDI)" to obtain Figure 1 An outer packaging material 1 for an electricity storage device is shown.

[0208] In the table, the adduct of trimethylolpropane and hexamethylene diisocyanate (HMDI) is referred to as “adduct A”, the adduct of pentaerythritol and hexamethylene diisocyanate (HMDI) is referred to as “adduct B”, and the adduct of trimethylolpropane and toluene diisocyanate (TDI) is referred to as “adduct C”.

[0209]

[0210]

[0211]

[0212] Each of the outer packaging materials for a power storage device obtained as described above was evaluated according to the following evaluation method. The results are shown in Tables 1 to 3.

[0213] <Moldability Evaluation Method>

[0214] The outer packaging material for a power storage device was stretch-molded using a stretch molding machine (product number: TP-25C-X2) manufactured by AMADA Co., Ltd. into a rectangular parallelepiped shape of 55 mm long x 35 mm wide x 8 mm deep. The moldability was evaluated based on the following criteria.

[0215] (Judgment Criteria)

[0216] “◎”…No pinholes or cracks at all.

[0217] "○" ... There were no pinholes or cracks at all, but slight white turbidity was observed in the protective layer.

[0218] “△”: Pinholes are generated only in a very small part, but there are practically no pinholes.

[0219] “×”… Pinholes and cracks occurred at the corners.

[0220] <Printability Evaluation Method>

[0221] Using an inkjet printer, a barcode was printed with white ink (dot size: 0.25 mm diameter) on the surface (outer surface) of the protective layer of each outer packaging material. The printability was then evaluated based on the following criteria, based on whether the printed barcode could be read without any problems using a barcode reader and whether the printed barcode exhibited bleeding.

[0222] (Judgment Criteria)

[0223] "◎" ...Can be read easily with a barcode reader. No bleeding.

[0224] "○" ...Can be read with a barcode reader without any problems. Slight bleeding occurs but is not a problem.

[0225] "△" ...Some bleeding was observed, but the barcode reader could read it without any problems.

[0226] "×" ... cannot be read with a barcode reader. Extensive bleeding.

[0227] <Solvent resistance evaluation method (ethanol)>

[0228] Each outer packaging material was cut into a 10 cm long x 10 cm wide test piece. 1 mL (1 cc) of ethanol was dripped onto the surface (outer surface) of the protective layer of the test piece. A sliding member made of cotton wrapped around a 1 cm diameter, 1 kg mass weight was then rubbed back and forth 10 times at the location where the droplet had landed on the test piece. The appearance of the protective layer surface (outer surface) of the test piece after 10 reciprocating strokes was visually inspected, and solvent (ethanol) resistance was evaluated according to the following criteria.

[0229] (Judgment Criteria)

[0230] “◎”…After 10 reciprocating cycles, the appearance remains unchanged.

[0231] "○" ... The appearance did not change until the 1st to 7th reciprocation, but the appearance changed after the 8th reciprocation.

[0232] "△" ... The appearance did not change until the 1st to 4th reciprocation, but the appearance changed after the 5th reciprocation.

[0233] "×" ... The appearance changed after one reciprocating stroke (poor solvent resistance).

[0234] <Solvent resistance evaluation method (methyl ethyl ketone)>

[0235] Solvent resistance (methyl ethyl ketone) was evaluated in the same manner as in the above-mentioned solvent resistance evaluation method (ethanol), except that 1 mL of methyl ethyl ketone (MEK) was used instead of 1 mL of ethanol. The evaluation criteria were the same as those in the above-mentioned solvent resistance evaluation method (ethanol).

[0236] As can be seen from the table, the packaging materials for power storage devices of Examples 1 to 15 of the present invention have excellent moldability, good printability, and excellent solvent resistance.

[0237] In contrast, Comparative Examples 1 to 5, which fall outside the specified range of the present invention, have the following problems: The outer packaging material of Comparative Example 1 has poor printability. Furthermore, the outer packaging materials of Comparative Examples 2 to 5 have significantly poor solvent resistance to MEK.

[0238] Industrial applicability

[0239] The outer packaging material for a power storage device and the outer packaging case for a power storage device according to the present invention can be used as outer packaging materials for various power storage devices. Specific examples of such power storage devices include:

[0240] ·Electrical storage devices such as lithium secondary batteries (lithium ion batteries, lithium polymer batteries, etc.);

[0241] Lithium-ion capacitors;

[0242] Electric double layer capacitors;

[0243] All-solid-state batteries; etc.

[0244] In addition, examples of the power storage device according to the present invention include the various power storage devices exemplified above.

[0245] This application claims the benefit of priority from Japanese Patent Application No. 2016-254888, filed on December 28, 2016, the disclosure of which is incorporated herein by reference.

[0246] The terms and descriptions used herein are for explaining the embodiments of the present invention and are not intended to limit the present invention. The present invention allows for any design changes within the scope of the claims as long as they do not exceed the gist of the invention.

Claims

1. An outer packaging material for an electrical storage device, characterized in that: The outer packaging material for a power storage device includes a base layer formed of a heat-resistant resin, a sealant layer as an inner layer, and a metal foil layer arranged between the base layer and the sealant layer. A protective layer is laminated on the surface of the base material layer opposite to the metal foil layer. The protective layer contains 40% by mass or more of a polyester resin, wherein the polyester resin is composed of a polyester polyol having a number average molecular weight of 8,000 to 50,000 and independently having a hydroxyl group or a carboxyl group at at least both ends, and a polyfunctional isocyanate curing agent containing at least an aliphatic polyfunctional isocyanate compound. The protective layer further contains a lubricant, which contains at least wax. The polyester resin constituting the protective layer is a polyester resin formed by the polyester polyol, the multifunctional isocyanate curing agent and a polyol having a valence of 3 or more, wherein the molecular weight of the polyol is smaller than the number average molecular weight of the polyester polyol. The aliphatic multifunctional isocyanate compound is an adduct of trimethylolpropane and an aliphatic diisocyanate compound.

2. The outer packaging material for a power storage device according to claim 1, wherein The equivalent ratio [NCO] / [OH+COOH], which is the ratio of the number of moles of isocyanate groups in the polyfunctional isocyanate curing agent to the total number of moles of the hydroxyl groups and the carboxyl groups, is 0.5 to 5.

3. The outer packaging material for a power storage device according to claim 1 or 2, wherein The protective layer contains solid particles with an average particle size of 1 μm to 10 μm.

4. The outer packaging material for an electrical storage device according to claim 1 or 2, wherein A colored layer is arranged between the base material layer and the metal foil layer.

5. The outer packaging material for a power storage device according to claim 4, wherein The base material layer and the colored layer are laminated and integrated with each other via an easy-adhesion layer. 6 . An outer casing for an electrical storage device, formed from the molded article of the outer casing material for an electrical storage device according to claim 1 .

7. An electric storage device, characterized in that have: a power storage device main body; and An outer packaging member comprising the outer packaging material for an electrical storage device according to any one of claims 1 to 5 and / or the outer packaging case for an electrical storage device according to claim 6, The power storage device main body is packaged by the packaging member.

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