Exterior material for power storage device and power storage device

Abstract

To provide an exterior material for a power storage device and a power storage device having excellent scratch resistance.SOLUTION: An exterior material for a power storage device used in a power storage device includes at least a base layer, a barrier layer, and a sealant layer in this order, in which the oxygen permeability of the sealant layer at 100°C is 1.0×10-15 to 1.0×10-13 [(mol m) / (m2 s Pa)].SELECTED DRAWING: Figure 1

Description

[Technical field]

[0001] The present disclosure relates to an exterior material for an electricity storage device and an electricity storage device. [Background technology]

[0002] Known examples of power storage devices include secondary batteries such as lithium ion batteries, nickel metal hydride batteries, and lead storage batteries, as well as electrochemical capacitors such as electric double layer capacitors. Due to the miniaturization of portable devices or the limitations of installation space, there is a demand for further miniaturization of power storage devices, and lithium ion batteries with high energy density have attracted attention. Metallic cans have traditionally been used as exterior materials for lithium ion batteries, but multilayer films that are lightweight, have high heat dissipation properties, and can be produced at low cost have come to be used.

[0003] A lithium ion battery using the above multilayer film as an exterior material is called a laminated lithium ion battery. A laminated lithium ion battery includes an electric storage element having a positive electrode, a liquid electrolyte, and a negative electrode, and an exterior bag that houses the electric storage element, and prevents moisture from penetrating into the battery. The exterior bag has an exterior material, and the exterior material includes a base layer, a barrier layer, and a sealant layer in this order. The exterior material covers the electric storage element with the sealant layer facing inward and the base layer facing outward. A laminated lithium ion battery is manufactured, for example, by forming a recess in a part of the exterior material by cold molding, housing the electric storage element in the recess, folding back the remaining part of the exterior material, and sealing the edge portion by heat sealing (see, for example, Patent Document 1). [Prior art documents] [Patent documents]

[0004] [Patent Document 1] JP 2013-101765 A Summary of the Invention [Problem to be solved by the invention]

[0005] Meanwhile, research and development of an energy storage device called an all-solid-state battery is being conducted as a next-generation battery of lithium-ion batteries. In order to increase the conductivity of the energy storage element, the all-solid-state battery is constrained and the energy storage element is operated while being pressurized via an exterior material. In order to operate the all-solid-state battery efficiently, it is necessary to apply pressure uniformly to the energy storage element.

[0006] However, in the battery manufacturing process, the sealant layer may be scratched in the transport direction when the exterior material is transported by rolls. If the sealant layer has such scratches, pressure may not be applied uniformly to the pressure-receiving surface of the energy storage element, which may reduce the operating efficiency of the battery. In addition, in electricity storage devices other than all-solid-state batteries, it is also desirable for the sealant layer to not be scratched in order to improve the performance of the electricity storage device. Therefore, there has been a demand for an exterior material for an electricity storage device that can have excellent scratch resistance.

[0007] The present disclosure has been made in consideration of the above-mentioned problems, and has an object to provide an exterior material for an electricity storage device that can have excellent scratch resistance, and an electricity storage device. [Means for solving the problem]

[0008] Means for Solving the Problems The inventors of the present disclosure conducted extensive research to solve the above problems and unexpectedly discovered that the scratch resistance of an exterior material can be improved by setting the oxygen permeability of a sealant layer within a specific range, which led to the present disclosure. That is, one aspect of the present disclosure is an exterior material for an electricity storage device used in an electricity storage device, the exterior material including at least a base layer, a barrier layer, and a sealant layer in this order, the sealant layer having an oxygen permeability of 1.0×10 at 100° C. -15 ~1.0×10 -13 [(mol m) / (m 2 The present invention provides an exterior material for an electricity storage device having a thermal conductivity of 1.0 s Pa.

[0009] The exterior material can have excellent scratch resistance. The inventors of the present disclosure speculate as follows about the reason why such an effect is achieved. That is, first, it is believed that the more amorphous regions there are in the sealant layer, the easier it is for oxygen to permeate, and the fewer amorphous regions there are, the harder the sealant layer is. Therefore, it is believed that if the crystallinity of the sealant layer is high, oxygen is less likely to permeate through the sealant layer, making the sealant layer harder, whereas if the crystallinity of the sealant layer is low, oxygen is more likely to permeate through the sealant layer, making the sealant layer softer. Therefore, when the oxygen permeability of the sealant layer is too low, when the packaging material is transported by the rolls and stress is applied to the sealant layer from the rolls, the sealant layer is soft, so that the stress from the rolls toward the barrier layer is easily transmitted to the inside of the sealant layer. However, the stress bounces off the barrier layer side, and the stress from the rolls is canceled by the stress of the rebound from the barrier layer side, so that the inside of the sealant layer is in a state where the stress is not easily applied as a whole. As a result, the stress from the rolls toward the barrier layer is not easily alleviated and is concentrated on the surface of the sealant layer on the roll side, making the surface of the sealant layer easily damaged. On the other hand, if the oxygen permeability of the sealant layer is too high, when the packaging material is transported by rolls and stress is applied to the sealant layer from the rolls, the sealant layer is hard, so the stress from the rolls toward the barrier layer is not easily transmitted to the inside of the sealant layer. As a result, the stress from the rolls toward the barrier layer is not easily alleviated and is concentrated on the surface of the sealant layer facing the rolls, making the surface of the sealant layer more susceptible to damage. In contrast, in the packaging material of the present disclosure, the oxygen permeability of the sealant layer is within an appropriate range, and the sealant layer is neither too soft nor too hard, so that the stress from the roll toward the barrier layer is appropriately transmitted to the inside of the sealant layer, and the concentration of stress on the surface of the sealant layer is accordingly suppressed. In other words, the stress from the roll toward the barrier layer is appropriately alleviated. As a result, the surface of the sealant layer is less susceptible to scratches, and the packaging material can have excellent scratch resistance.

[0010] In the above-mentioned exterior packaging material for a storage battery device, the sealant layer may contain a base resin (A) made of a polypropylene-based resin, the polypropylene-based resin may contain at least one of a homopolypropylene and a block polypropylene, and the polypropylene-based resin may have a crystallization temperature of 100 to 120°C and a melting temperature of 155 to 168°C. In this exterior material, the polypropylene-based resin contained in the base resin contains at least one of homopolypropylene and block polypropylene, and the polypropylene-based resin has a crystallization temperature of 100 to 120°C and a melting temperature of 155 to 168°C, which enables the exterior material to have sufficient hardness. When the polypropylene is composed only of random polypropylene, the scratch resistance of the exterior material is improved compared to when the crystallization temperature or melting temperature of the polypropylene-based resin is outside the above range.

[0011] In the above-mentioned exterior packaging material for an electricity storage device, the sealant layer may contain a base resin (A) made of a polypropylene-based resin, and the polypropylene-based resin may contain a first polypropylene-based resin having an MFR of 15 to 40 g / 10 min and a second polypropylene-based resin having an MFR of 1 to 10 g / 10 min. The first polypropylene resin with a high MFR tends to be relatively hard because the molecules are easy to move and crystallize easily, whereas the second polypropylene resin with a low MFR tends to be relatively soft because crystallization does not easily proceed. Therefore, by including a first polypropylene resin with a high MFR and a second polypropylene resin with a low MFR in the polypropylene resin, the sealant layer is given an appropriate stress relaxation property, and the exterior material can have better scratch resistance.

[0012] In the above-mentioned exterior material for a storage battery device, the sealant layer comprises a base resin (A) made of a polypropylene-based resin, and an additive (B), the additive (B) comprises a component having a crystallization temperature of 50 to 90°C and a melting temperature of 50 to 120°C, and the component may comprise at least one of a compatible elastomer component (B1) that is compatible with the base resin (A), an incompatible elastomer component (B2) that is incompatible with the base resin (A), a block copolymer or graft copolymer (B3) of polypropylene and polyethylene, and a block copolymer (B4) of polyethylene and ethylenebutylene. In this case, by including the above-mentioned additive in the sealant layer in addition to the base resin, the stress relaxation property is more effectively imparted to the sealant layer, and the exterior material can have even better scratch resistance.

[0013] In the above-mentioned exterior material for an electricity storage device, the components include the incompatible elastomer component (B2) and a block copolymer of polypropylene and polyethylene (B3) or a block copolymer of polyethylene and ethylenebutylene (B4), and the incompatible elastomer component (B2) may be a polyethylene-based elastomer component. When the additive contains the above-mentioned component, stress relaxation properties are effectively imparted to the sealant layer, and the dispersibility of the additive is further improved, resulting in further improved scratch resistance of the exterior material.

[0014] In the exterior packaging material for an electricity storage device, the electricity storage device may be an all-solid-state battery. The exterior material for an electric storage device can have excellent scratch resistance, so that unevenness is unlikely to form on the surface of the sealant layer. Therefore, when the exterior material for an electric storage device is used as an exterior material for an all-solid-state battery including an electric storage element, and the electric storage element is pressurized through the exterior material, the presence of areas where the pressure is high and areas where the pressure is low on the pressurized surface of the electric storage element is suppressed, and the pressurized surface of the electric storage element is uniformly pressurized. As a result, the all-solid-state battery as an electric storage device can be operated efficiently.

[0015] Another aspect of the present disclosure provides an electricity storage device including an electricity storage element and an outer bag that houses the electricity storage element, the outer bag having the above-mentioned outer casing material. According to the electric storage device, the exterior material for the electric storage device can have excellent scratch resistance, so that unevenness is unlikely to form on the surface of the sealant layer. Therefore, when the exterior material for the electric storage device is used as an exterior material for an electric storage device including an electric storage element, and the electric storage element is pressurized through the exterior material, the presence of areas where the pressure is high and areas where the pressure is low on the pressurized surface of the electric storage element is suppressed, and the pressurized surface of the electric storage element is uniformly pressurized. As a result, the performance of the electric storage device can be improved. The power storage device may be an all-solid-state battery. In this case, the pressure-receiving surface of the electricity storage element is uniformly pressurized, so that the all-solid-state battery as an electricity storage device can be operated efficiently. Effect of the Invention

[0016] According to the present disclosure, there are provided an exterior material for an electricity storage device and an electricity storage device capable of having excellent scratch resistance. [Brief description of the drawings]

[0017] [Figure 1] FIG. 1 is a schematic cross-sectional view of an exterior material according to an embodiment of the present disclosure. [Diagram 2] 2 is a schematic cross-sectional view showing a modified example of the exterior material of FIG. 1. [Diagram 3] FIG. 1 is a perspective view illustrating an electricity storage device according to an embodiment of the present disclosure. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0018] Hereinafter, preferred embodiments of the present disclosure will be described in detail with reference to the drawings. In the drawings, the same or corresponding parts are denoted by the same reference numerals, and duplicated explanations are omitted. In addition, the dimensional ratios of the drawings are not limited to the ratios shown in the drawings.

[0019] [Exterior materials for energy storage devices] Fig. 1 is a cross-sectional view that typically illustrates an exterior material for an electricity storage device according to an embodiment of the present disclosure. As shown in Fig. 1, an exterior material for an electricity storage device (hereinafter, also simply referred to as "exterior material") 10 of this embodiment is an exterior material used for an electricity storage device, and includes a base layer 11, a first adhesive layer 12a, a barrier layer 13, an adhesive resin layer 15, and a sealant layer 16, in this order. Here, the oxygen permeability of the sealant layer 16 at 100°C is 1.0 x 10 -15 ~1.0×10 -13 [(mol m) / (m 2 s·Pa). This exterior material 10 can have excellent scratch resistance.

[0020] The barrier layer 13 has a first anti-corrosion treatment layer 14a on the substrate layer 11 side, and a second anti-corrosion treatment layer 14b on the sealant layer 16 side. In the packaging material 10, the substrate layer 11 is the outermost layer, and the sealant layer 16 is the innermost layer. That is, the packaging material 10 is used with the substrate layer 11 facing the outside of the electricity storage device, and the sealant layer 16 facing the inside of the electricity storage device.

[0021] Each layer constituting the packaging material 10 will now be described in detail.

[0022] <Base material layer> The base layer 11 imparts heat resistance in a sealing process when manufacturing an electricity storage device and plays a role in suppressing the occurrence of pinholes that may occur during molding and distribution. In particular, in the case of an exterior material for a large-scale electricity storage device, the base layer 11 can also impart scratch resistance, chemical resistance, insulation, and the like.

[0023] The base layer 11 is preferably a layer formed of an insulating resin, such as polyester resin, polyamide resin, polyimide resin, polyamideimide resin, polyetherketone resin, polyphenylene sulfide resin, polyetherimide resin, polysulfone resin, fluororesin, phenol resin, melamine resin, urethane resin, allyl resin, silicone resin, epoxy resin, furan resin, acetyl cellulose resin, or the like.

[0024] Among these resins, polyester resin and polyamide resin are preferable for the base layer 11 because of their excellent moldability. Examples of polyester resin include polyethylene terephthalate, polybutylene terephthalate, and polyethylene naphthalate. Examples of polyamide resin include nylon 6, nylon 6,6, a copolymer of nylon 6 and nylon 6,6, nylon 6, nylon 9T, nylon 10, polymetaxylylene adipamide (MXD6), nylon 11, and nylon 12.

[0025] The substrate layer 11 may be in the form of a stretched or unstretched film, or in the form of a coating film. The substrate layer 11 may be a single layer or a multilayer. When the substrate layer 11 is a multilayer, it is formed by laminating layers made of different resins. When the substrate layer 11 is in the form of a film, it may be a co-extruded film or a laminated film using an adhesive. When the substrate layer 11 is a coating film, it may be a coating film obtained by coating a composition for forming a coating film multiple times. The substrate layer 11 may be a multilayer film by combining a film and a coating film.

[0026] When the above-mentioned resin is used in the form of a film, the base layer 11 is preferably a biaxially stretched film. In this case, the moldability of the packaging material 10 is improved. Examples of the stretching method for the biaxially stretched film include a sequential biaxial stretching method, a tubular biaxial stretching method, and a simultaneous biaxial stretching method. From the viewpoint of obtaining better deep-draw moldability, the biaxially stretched film is preferably a film stretched by a tubular biaxial stretching method.

[0027] The thickness of the substrate layer 11 is preferably 6 to 100 μm, more preferably 10 to 75 μm, and even more preferably 10 to 50 μm. When the thickness of the substrate layer 11 is 6 μm or more, the pinhole resistance and insulating properties of the packaging material 10 tend to be improved. When the thickness of the substrate layer 11 is 100 μm or less, the total thickness of the packaging material 10 can be reduced.

[0028] In addition, it is preferable that the base material layer 11 has a melting temperature higher than that of the sealant layer 16. When the sealant layer 16 has a multi-layer structure, the melting temperature of the sealant layer 16 means the melting temperature of the layer with the highest melting temperature. By making the base material layer 11 have a melting temperature higher than that of the sealant layer 16, it is possible to prevent the appearance of the packaging material 10 from deteriorating due to melting of the base material layer 11 (outer layer) during heat sealing.

[0029] The melting temperature of the base layer 11 is preferably 290° C. or higher. However, the melting temperature of the base layer 11 is preferably 350° C. or lower. Examples of resin films that can be used as the base layer 11 and have a melting temperature within the above range include nylon films, polyester films such as PET films, polyamide films, and polyphenylene sulfide films (PPS films). The base layer 11 may be a commercially available film, or may be formed by coating (application of a coating liquid and drying). The base layer 11 may be formed by coating a thermosetting resin. Furthermore, the base layer 11 may contain, for example, various additives (for example, a flame retardant, a slip agent, an antiblocking agent, an antioxidant, a light stabilizer, a tackifier, etc.).

[0030] Melting temperature T of the base layer 11 11 and the melting temperature T of the sealant layer 16 16 The difference (T 11 -T 16 ) is preferably 20° C. or more. When this temperature difference is 20° C. or more, deterioration of the appearance of the packaging material 10 due to heat sealing can be more sufficiently suppressed.

[0031] <First adhesive layer 12a> The first adhesive layer 12a is a layer that bonds the base material layer 11 and the barrier layer 13. Specific examples of materials constituting the first adhesive layer 12a include polyurethane resins in which a bifunctional or higher isocyanate compound (polyfunctional isocyanate compound) acts as a curing agent on a base material such as polyester polyol, polyether polyol, acrylic polyol, or carbonate polyol. The above-mentioned various polyols can be used alone or in combination of two or more types depending on the functions and performance required for the exterior material 10. In addition, materials constituting the first adhesive layer 12a can also be used that use an epoxy resin as a base material and a curing agent in addition to the above.

[0032] The first adhesive layer 12a is formed using an adhesive composition containing the above-mentioned base agent and curing agent. In addition, the first adhesive layer 12a may contain various other additives and stabilizers in the above-mentioned adhesive composition depending on the performance required for the adhesive layer.

[0033] The adhesive composition preferably contains at least one polyfunctional isocyanate compound selected from the group consisting of alicyclic isocyanate polymers and isocyanate polymers containing an aromatic ring in the molecular structure as a curing agent. Examples of the polyfunctional isocyanate compound include a nurate of isophorone diisocyanate, an adduct of tolylene diisocyanate, an adduct of hexamethylene diisocyanate, a biuret and a nurate of hexamethylene diisocyanate, a biuret and a nurate of tolylene diisocyanate, an adduct, a biuret and a nurate of diphenylmethane diisocyanate, and an adduct, a biuret and a nurate of xylylene diisocyanate.

[0034] As the curing agent, an alicyclic isocyanate polymer may be used in combination with an isocyanate polymer containing an aromatic ring in the molecular structure. By using these in combination, the heat resistance tends to be further improved.

[0035] From the viewpoint of further improving heat resistance, the adhesive composition preferably contains at least one polyol selected from the group consisting of polyester polyol, acrylic polyol, and polycarbonate diol. Among these, from the viewpoint of further improving heat resistance, polyester polyol is more preferable.

[0036] In the adhesive composition, the ratio (NCO / OH) of the number of isocyanate groups contained in the polyfunctional isocyanate compound to the number of hydroxyl groups contained in the polyol may be 1.5 to 40.0, or may be 15.0 to 30.0. If this ratio is 1.5 or more, the curing agents react with each other, and by-products such as urea resin and biuret resin are easily generated. Since these by-products contain active hydrogen groups, they interact with polar groups of adjacent layers, and the interfacial adhesion between the first adhesive layer 12a and the base material layer 11 and the barrier layer 13 is further improved. Therefore, the heat resistance of the packaging material 10 tends to be improved. On the other hand, if the ratio is 40.0 or less, the laminate strength of the packaging material 10 can be further improved in room temperature and high temperature environments.

[0037] The thickness of the first adhesive layer 12a is not particularly limited, but from the viewpoint of obtaining the desired adhesive strength, followability, processability, etc., it is preferably, for example, 1 to 10 μm, and more preferably 2 to 7 μm.

[0038] The mass per unit area of ​​the first adhesive layer 12a is set to 2.0 to 6.0 g / m from the viewpoint of ensuring superior lamination strength both in room temperature and high temperature environments and obtaining superior deep drawability. 2 and 2.5 to 5.0 g / m 2 and 3.0 to 4.0 g / m 2 may be also possible.

[0039] <Barrier layer> The barrier layer 13 has a water vapor barrier property that prevents moisture from penetrating into the inside of the electricity storage device. The barrier layer 13 may also have extensibility for deep drawing. As the barrier layer 13, for example, various metal foils such as aluminum, stainless steel, and copper, or metal vapor deposition films, inorganic oxide vapor deposition films, carbon-containing inorganic oxide vapor deposition films, and films provided with these vapor deposition films can be used. Examples of films having a vapor deposition layer include aluminum vapor deposition films and inorganic oxide vapor deposition films. These may be used alone or in combination of two or more. As the barrier layer 13, in terms of mass (specific gravity), barrier properties such as moisture resistance, processability, and cost, a metal foil is preferred, and an aluminum foil or a stainless steel foil is more preferred.

[0040] As the aluminum foil, a soft aluminum foil that has been annealed can be preferably used because it can impart the desired ductility during molding. In order to impart further pinhole resistance and ductility during molding, it is more preferable to use an aluminum foil containing iron. The iron content in the aluminum foil is preferably 0.1 to 9.0 mass%, and more preferably 0.5 to 2.0 mass%, based on 100 mass% of the aluminum foil. When the iron content is 0.1 mass% or more, an exterior material 10 having better pinhole resistance and ductility can be obtained. When the iron content is 9.0 mass% or less, an exterior material 10 having better flexibility can be obtained. As the aluminum foil, untreated aluminum foil may be used, but it is preferable to use aluminum foil that has been subjected to a degreasing treatment in order to impart corrosion resistance. When the aluminum foil is subjected to a degreasing treatment, the degreasing treatment may be performed on only one side of the aluminum foil or on both sides of the aluminum foil.

[0041] The thickness of the barrier layer 13 is not particularly limited, but taking into consideration the barrier properties, pinhole resistance, and processability, it is preferably 9 to 200 μm, and more preferably 15 to 100 μm.

[0042] <First and second corrosion prevention treatment layers> The first and second corrosion prevention treatment layers 14a, 14b are layers provided to prevent corrosion of the metal foil (metal foil layer) constituting the barrier layer 13. The first corrosion prevention treatment layer 14a serves to increase the adhesion between the barrier layer 13 and the first adhesive layer 12a. The second corrosion prevention treatment layer 14b serves to increase the adhesion between the barrier layer 13 and the adhesive resin layer 15. The first anti-corrosion treatment layer 14a and the second anti-corrosion treatment layer 14b may be layers having the same configuration, or may be layers having different configurations. The first and second corrosion prevention treatment layers 14a, 14b (hereinafter also simply referred to as "corrosion prevention treatment layers 14a, 14b") are formed, for example, by degreasing treatment, hydrothermal conversion treatment, anodizing treatment, chemical conversion treatment, or a combination of these treatments.

[0043] The degreasing treatment includes acid degreasing and alkaline degreasing. Examples of acid degreasing include a method using an inorganic acid such as sulfuric acid, nitric acid, hydrochloric acid, or hydrofluoric acid alone or a mixture of these. In addition, in acid degreasing, it is preferable to use an acid degreasing agent in which a fluorine-containing compound such as monosodium ammonium difluoride is dissolved in the inorganic acid. In this case, the aluminum degreasing effect can be obtained, particularly when an aluminum foil is used for the barrier layer 13. Furthermore, the acid degreasing agent can form a fluoride of aluminum, which is a passive state, and is effective in terms of corrosion resistance. The alkaline degreasing method includes a method using sodium hydroxide or the like.

[0044] An example of the hydrothermal modification treatment is a boehmite treatment in which an aluminum foil is immersed in boiling water containing added triethanolamine. An example of the anodizing treatment is an alumite treatment.

[0045] The chemical conversion treatment may be of the immersion type or coating type. Examples of the immersion type chemical conversion treatment include chromate treatment, zirconium treatment, titanium treatment, vanadium treatment, molybdenum treatment, calcium phosphate treatment, strontium hydroxide treatment, cerium treatment, ruthenium treatment, and various chemical conversion treatments consisting of a mixture of these treatments. On the other hand, coating-type chemical conversion treatments include a method in which a coating agent having anticorrosive properties is applied onto the barrier layer 13 .

[0046] When forming at least a part of the corrosion prevention layer by any of these corrosion prevention treatments, namely, hydrothermal conversion treatment, anodizing treatment, and chemical conversion treatment, it is preferable to perform the above-mentioned degreasing treatment in advance. When using a degreased metal foil, such as a metal foil that has been subjected to an annealing process, as the barrier layer 13, there is no need to perform a degreasing treatment again in forming the corrosion prevention layers 14a and 14b.

[0047] The coating agent used in the spray-type chemical conversion treatment preferably contains trivalent chromium. The coating agent may also contain at least one polymer selected from the group consisting of cationic polymers and anionic polymers, which will be described later.

[0048] Among the above treatments, particularly hydrothermal conversion treatment and anodizing treatment dissolve the aluminum foil surface with a treatment agent to form aluminum compounds (boehmite, alumite) with excellent corrosion resistance. Therefore, a form in which a bicontinuous structure is formed from the barrier layer 13 using the aluminum foil to the corrosion prevention treatment layers 14a, 14b is obtained, and the above treatments are included in the definition of chemical conversion treatment. On the other hand, it is also possible to form the corrosion prevention treatment layers 14a, 14b by a pure coating method that is not included in the definition of chemical conversion treatment, as described later. For example, this method uses a sol of a rare earth element oxide such as cerium oxide having an average particle size of 100 nm or less, which has an aluminum corrosion prevention effect (inhibitor effect) and is also environmentally friendly. By using this method, it is possible to impart a corrosion prevention effect to metal foil such as aluminum foil, even with a general coating method.

[0049] Examples of the rare earth element oxide sol include sols using various solvents such as water-based, alcohol-based, hydrocarbon-based, ketone-based, ester-based, ether-based, etc. Among these, water-based sols are preferred.

[0050] In order to stabilize the dispersion of the rare earth element oxide sol, inorganic acids such as nitric acid, hydrochloric acid, phosphoric acid, etc. or their salts, and organic acids such as acetic acid, malic acid, ascorbic acid, lactic acid, etc. are usually used as dispersion stabilizers. Among these dispersion stabilizers, phosphoric acid in particular is expected to provide the following effects (1) to (4) in the exterior packaging material 10. (1) Dispersion stabilization of sol (2) Improved adhesion to the barrier layer 13 by utilizing the aluminum chelating ability of phosphoric acid (3) Imparting corrosion resistance by capturing aluminum ions (passivation) (4) The dehydration and condensation of phosphoric acid occurs easily even at low temperatures, improving the cohesive strength of the corrosion prevention treatment layers (oxide layers) 14a and 14b.

[0051] The corrosion prevention layers 14a and 14b formed from the rare earth oxide sol are aggregates of inorganic particles, and therefore may lose their cohesive strength even after the drying and curing process. Therefore, it is preferable that the corrosion prevention layers 14a and 14b in this case are compounded with an anionic polymer or a cationic polymer to compensate for the cohesive strength.

[0052] The corrosion prevention treatment layers 14a, 14b are not limited to the above-mentioned layers. For example, they may be formed using a treatment agent in which phosphoric acid and a chromium compound are mixed with a resin binder (such as aminophenol), as in the case of coating-type chromate, which is a known technology. By using this treatment agent, a layer having both corrosion prevention function and adhesion can be formed. In addition, although it is necessary to consider the stability of the coating liquid, a coating agent in which a rare earth oxide sol and a polycationic polymer or a polyanionic polymer are mixed in advance into a one-component solution can be used to form a layer having both corrosion prevention function and adhesion.

[0053] The mass per unit area of ​​the corrosion prevention layers 14a and 14b is 0.005 to 0.200 g / m2 regardless of whether the layer has a multi-layer structure or a single-layer structure. 2 It is preferable that the thickness is 0.010 to 0.100 g / m 2 It is more preferable that the mass per unit area is 0.005 g / m. 2 If the mass per unit area is 0.200 g / m or more, it is easy to impart a corrosion prevention function to the barrier layer 13. 2 Even if the thickness exceeds 100 mm, the corrosion prevention function does not change much. On the other hand, when a rare earth oxide sol is used, if the coating is thick, the heat curing during drying may be insufficient, which may result in a decrease in cohesive force. The thickness of the corrosion prevention layers 14a and 14b can be calculated from their specific gravity.

[0054] From the viewpoint of easily maintaining the adhesion between the sealant layer 16 and the barrier layer 13, the corrosion prevention treatment layers 14a, 14b may be in an embodiment containing, for example, cerium oxide, 1 to 100 parts by mass of phosphoric acid or a phosphate relative to 100 parts by mass of the cerium oxide, and a cationic polymer, or may be formed by subjecting the barrier layer 13 to a chemical conversion treatment, or may be formed by subjecting the barrier layer 13 to a chemical conversion treatment and contain a cationic polymer.

[0055] <Sealant layer> The sealant layer 16 is a layer that imparts heat-sealing sealability to the exterior material 10, and is a layer that is placed on the inside and heat-sealed (thermally fused) when the electricity storage device is assembled. The oxygen permeability of the sealant layer 16 at 100° C. is 1.0×10 -15 ~1.0×10 -13 [(mol m) / (m 2 ·s·Pa). The oxygen permeability of the sealant layer 16 at 100° C. is preferably 7.0×10 -15 ~5.0×10 -14 [(mol m) / (m 2 s Pa)], and more preferably 9.0 × 10 -15 ~3.0×10 -14 [(mol m) / (m 2 s·Pa). Oxygen permeability is 7.0 x 10 -15 [(mol m) / (m 2 When the oxygen permeability is 5.0×10 s·Pa or more, the sealant layer 16 becomes relatively hard, so that when the packaging material 10 is transported by rolls and stress is applied from the rolls to the sealant layer 16, the stress directed from the rolls to the barrier layer 13 is suppressed from rebounding from the barrier layer 13 side. Therefore, the stress directed from the rolls to the barrier layer 13 is easily alleviated, and the surface of the sealant layer is less likely to be damaged. On the other hand, when the oxygen permeability is 5.0×10 -14 [(mol m) / (m 2If the compressive strength is less than or equal to 1.·s·Pa), the sealant layer becomes relatively soft. Therefore, when the exterior packaging material 10 is transported by rolls and stress is applied from the rolls to the sealant layer 16, the stress from the rolls to the barrier layer 13 is easily alleviated, and the surface of the sealant layer 16 is less likely to be damaged.

[0056] The sealant layer 16 contains a base resin (A) made of a polypropylene-based resin. The sealant layer 16 may or may not further contain an additive (B).

[0057] The polypropylene-based resin is a resin obtained from a polymer monomer containing propylene. Examples of the polypropylene-based resin include homopolypropylene, block polypropylene, and random polypropylene. These may be used alone or in combination of two or more. The polypropylene-based resin preferably contains at least one of homopolypropylene and block polypropylene. When the polypropylene contains at least one of homopolypropylene and block polypropylene, the exterior material 10 can have sufficient hardness, and the scratch resistance of the exterior material 10 is further improved compared to when the polypropylene is composed of only random polypropylene. Here, the polypropylene-based resin preferably contains block polypropylene.

[0058] The crystallization temperature of the polypropylene resin is not particularly limited, but is preferably 100 to 120°C. In this case, the packaging material 10 can have sufficient hardness, and the scratch resistance of the packaging material 10 is improved compared to when the crystallization temperature of the polypropylene-based resin is outside the above range. From the viewpoint of further improving the scratch resistance of the packaging material 10, the crystallization temperature of the polypropylene-based resin is preferably 102 to 120°C, and more preferably 105 to 115°C.

[0059] The melting temperature of the polypropylene resin is not particularly limited, but is preferably 155 to 168°C. In this case, it becomes possible for the exterior material 10 to have sufficient hardness, and the scratch resistance of the exterior material 10 is further improved, compared to when the melting temperature of the polypropylene-based resin is outside the above range. From the viewpoint of further improving the scratch resistance of the exterior material 10, the melting temperature of the polypropylene-based resin is preferably 157 to 167°C, and more preferably 160 to 166°C.

[0060] The melting temperature-crystallization temperature is not particularly limited and may be, for example, 30 to 70° C. The melting temperature-crystallization temperature is preferably 40 to 65° C., and more preferably 50 to 60° C. In this case, the sealant layer 16 exhibits a good balance between hardness and softness.

[0061] The polypropylene resin preferably contains a first polypropylene resin having an MFR of 15 to 40 g / 10 min and a second polypropylene resin having an MFR of 1 to 10 g / 10 min. The first polypropylene resin having a high MFR tends to be relatively hard because the molecules are easy to move and crystallize easily, whereas the second polypropylene resin having a low MFR tends to be relatively soft because crystallization does not easily proceed. Therefore, by including a first polypropylene resin having a high MFR and a second polypropylene resin having a low MFR in the polypropylene resin, the sealant layer 16 is given an appropriate stress relaxation property, and the exterior material 10 can have better scratch resistance.

[0062] The MFR of the first polypropylene resin is preferably from 20 to 35 g / 10 min, and more preferably from 23 to 30 g / 10 min. The MFR of the second polypropylene resin is preferably from 2 to 8 g / 10 min, and more preferably from 3 to 5 g / 10 min.

[0063] The ratio R of the MFR of the first polypropylene resin to the MFR of the second polypropylene resin is preferably greater than zero. In this case, the sealant layer 16 becomes relatively hard, so that when the packaging material 10 is transported by rolls and stress is applied from the rolls to the sealant layer 16, the stress directed from the rolls to the barrier layer 13 is prevented from rebounding from the barrier layer 13. This makes it easier to alleviate the stress directed from the rolls to the barrier layer 13, and the surface of the sealant layer becomes less susceptible to damage. The ratio R of the MFR is preferably 3 or more, and more preferably 5 or more. The ratio R of the MFR is preferably equal to or greater than 5. In this case, the sealant layer 16 becomes relatively soft, and therefore, when the packaging material 10 is transported by rolls and stress is applied from the rolls to the sealant layer 16, the stress from the rolls to the barrier layer 13 is easily alleviated, and the surface of the sealant layer 16 is less likely to be damaged. The ratio R of the MFR is preferably 20 or less, and more preferably 15 or less.

[0064] The additive (B) is not particularly limited, but preferably contains a component having a crystallization temperature of 50 to 90°C and a melting temperature of 50 to 120°C. When the crystallization temperature and melting temperature of the above components are 50°C or higher, appropriate softness can be imparted to the sealant layer 16, so that when the packaging material 10 is transported with rolls and stress is applied from the rolls to the sealant layer 16, the stress from the rolls toward the barrier layer 13 is easily alleviated, and the surface of the sealant layer 16 is less likely to be damaged. When the crystallization temperature of the above components is 90°C or lower or the melting temperature is 120°C or lower, the sealant layer 16 becomes relatively hard, so that when the packaging material 10 is transported with rolls and stress is applied from the rolls to the sealant layer 16, the stress from the rolls toward the barrier layer 13 is prevented from rebounding from the barrier layer 13 side. Therefore, the stress from the rolls toward the barrier layer 13 is easily alleviated, and the surface of the sealant layer is less likely to be damaged.

[0065] The crystallization temperature of the above components is preferably 55 to 85°C, and more preferably 60 to 80°C, from the viewpoint of further improving the scratch resistance of the packaging material 10.

[0066] The melting temperature of the above components is preferably 55 to 115°C, and more preferably 65 to 110°C, from the viewpoint of further improving the scratch resistance of the packaging material 10.

[0067] The additive (B) is not particularly limited, but preferably contains a component having a crystallization temperature of 50 to 90°C and a melting temperature of 50 to 120°C.

[0068] The melting temperature-crystallization temperature is not particularly limited, but from the viewpoint of stress relaxation, it is preferably 10 to 45°C, more preferably 15 to 40°C, and particularly preferably 20 to 35°C.

[0069] The above components may include at least one of a compatible elastomer component (B1) that is compatible with the base resin (A), an incompatible elastomer component (B2) that is incompatible with the base resin (A), a block copolymer or graft copolymer (B3) of polypropylene and polyethylene, and a block copolymer (B4) of polyethylene and ethylenebutylene. In this case, since the sealant layer 16 contains the above-mentioned additive (B) in addition to the base resin, the sealant layer 16 is more effectively imparted with stress relaxation properties, and the exterior packaging material 10 can have even better scratch resistance.

[0070] The compatible elastomer component (B1) means a component which, when melt-mixed with the base resin (A), disperses in the base resin (A) and has a dispersed phase with a size of less than 500 nm. Examples of the compatible elastomer component (B1) include polyolefin-based elastomer components. The polyolefin-based elastomer component is an elastomer component having a structure derived from an olefin. Examples of the polyolefin-based component include polypropylene-based elastomer components. The polypropylene-based elastomer component is an elastomer having a structure derived from propylene. Specific examples of the polypropylene-based elastomer component include copolymers of propylene and α-olefins. Examples of α-olefins include 1-butene, 1-pentene, 1-hexene, 1-octene, and 4-methyl-1-pentene. Examples of the copolymers include random copolymers and block copolymers.

[0071] The incompatible elastomer component (B2) means a component which, when melt-mixed with the base resin (A), disperses in the base resin (A) with a dispersed phase having a size of 500 nm or more and less than 500 μm. Examples of the incompatible elastomer component (B2) include polyolefin elastomer components. The polyolefin elastomer component is an elastomer component having a structure derived from olefin. Examples of the polyolefin elastomer component include polyethylene elastomer components, polybutene elastomer components, and polymethylpentene elastomer components. The polyethylene-based elastomer component is an elastomer component having a structure derived from ethylene. The polybutene-based component is an elastomer component having a structure derived from butene. The polymethylpentene-based component is an elastomer component having a structure derived from methylpentene.

[0072] As the polyolefin-based elastomer component, a polyethylene-based elastomer component is preferred from the viewpoint of stress relaxation. The polyethylene elastomer component is preferably a copolymer of ethylene and an α-olefin. Examples of the α-olefin include 1-butene, 1-pentene, 1-hexene, 1-octene, and 4-methyl-1-pentene. Examples of the copolymer include random copolymers and block copolymers.

[0073] The content of the ethylene-derived structure in the polyethylene-based elastomer component may be 60 mass % or more, 70 mass % or more, 80 mass % or more, or 90 mass % or more based on the total amount of the polyethylene-based component.

[0074] The content of the polyolefin elastomer component in the incompatible elastomer component (B2) may be 60 mass % or more, 70 mass % or more, 80 mass % or more, or 90 mass % or more based on the total amount of the component (B1).

[0075] The above components may include a polyethylene-based elastomer component as the incompatible elastomer component (B2), and a block copolymer of polypropylene and polyethylene (B3) or a block copolymer of polyethylene and ethylenebutylene (B4). When the additive (B) contains the above-mentioned components, stress relaxation properties are effectively imparted to the sealant layer 16, and the dispersibility of the additive (B) is further improved, resulting in further improved scratch resistance of the exterior packaging material 10.

[0076] The mass ratio of the incompatible elastomer component (B2) to the block copolymer (B3) of polypropylene and polyethylene or the block copolymer (B4) of polyethylene and ethylenebutylene may be 0.1 or more and less than 20, preferably 0.3 to 10, and more preferably 0.4 to 5.

[0077] The content of the additive (B) in the sealant layer 16 may be 2.5% by mass or more. The content of the additive (B) in the sealant layer 16 is preferably 5% by mass or more, and more preferably 10% by mass or more. When the content of the additive (B) in the sealant layer 16 is 2.5 mass % or more, the scratch resistance of the exterior packaging material 10 is further improved. The content of the additive (B) in the sealant layer 16 may be less than 50% by mass. The content of the additive (B) in the sealant layer 16 is preferably 30% by mass or less, and more preferably 20% by mass or less. When the content of the additive (B) in the sealant layer 16 is less than 50 mass %, the sealant layer 16 can be imparted with an appropriate degree of hardness.

[0078] The total content of the base resin (A) and the additive (B) in the sealant layer 16 may be 70 mass % or more, 80 mass % or more, or 90 mass % or more.

[0079] The proportion of the base resin (A) in the total mass of the base resin (A) and the additive (B) may be, for example, 70 mass% or more, 80 mass% or more, or 90 mass% or more, and may be 93 mass% or less, 95 mass% or less, or 97 mass% or less.

[0080] In addition to the above-mentioned base resin (A) and additive (B), the sealant layer 16 may contain other additive components as necessary, such as slip agents, antiblocking agents, antioxidants, light stabilizers, crystal nucleating agents, and flame retardants. The content of these additive components is preferably 5% by mass or less, assuming the total mass of the sealant layer 16 to be 100% by mass.

[0081] From the viewpoint of improving the scratch resistance of the exterior material 10, the ratio of the thickness of the sealant layer 16 to the thickness of the adhesive resin layer 15 (thickness of sealant layer 16 / thickness of adhesive resin layer 15) is preferably 1 or more, more preferably 1.1 or more, and particularly preferably 1.5 or more. From the viewpoint of improving the scratch resistance of the exterior packaging material 10, the ratio of the thickness of the sealant layer 16 to the thickness of the adhesive resin layer 15 (thickness of sealant layer 16 / thickness of adhesive resin layer 15) is preferably 10 or less, and more preferably 3 or less.

[0082] The total thickness of the sealant layer 16 and the adhesive resin layer 15 may be 15 to 300 μm, and from the viewpoints of sealing properties and water vapor barrier properties, it is preferably 25 to 150 μm, and more preferably 50 to 100 μm.

[0083] <Adhesive resin layer> The adhesive resin layer 15 is a layer that bonds the sealant layer 16 and the barrier layer 13, and contains an adhesive resin. The oxygen permeability of the adhesive resin layer 15 at 100° C. is not particularly limited. However, from the viewpoint of further improving the scratch resistance of the exterior packaging material 10, it is preferably 1.0×10 -15 ~1.0×10 -13 [(mol m) / (m 2 s·Pa)] is preferable. The adhesive resin layer 15 preferably has an oxygen permeability of 7.0×10 -15 ~5.0×10 -14 [(mol m) / (m 2 s Pa)], and more preferably 9.0 × 10 -15 ~3.0×10 -14 [(mol m) / (m 2 s·Pa).

[0084] The crystallization temperature of the adhesive resin layer 15 is not particularly limited, but is preferably 100 to 120°C. In this case, it becomes possible for the exterior material 10 to have sufficient hardness, and the scratch resistance of the exterior material 10 is improved compared to when the crystallization temperature of the polypropylene-based resin is outside the above range. The crystallization temperature of the polypropylene resin is preferably 102 to 120°C, more preferably 105 to 115°C, from the viewpoint of further improving the scratch resistance of the packaging material 10.

[0085] The adhesive resin layer 15 is not particularly limited as long as it contains a resin that bonds the sealant layer 16 and the barrier layer 13, and examples of such resins include acid-modified polyolefin resins.

[0086] The acid-modified polyolefin resin may be a polyolefin resin modified with maleic anhydride, carboxylic acid, sulfonic acid, or a derivative thereof. The acid-modified polyolefin resin may be, for example, a graft copolymer, a block copolymer, or a random copolymer. From the viewpoint of adhesion to the barrier layer 13, the acid-modified polyolefin resin is preferably a polyolefin resin graft-modified with maleic anhydride.

[0087] The adhesive resin layer 15 may contain various additives, as necessary, such as various compatible and incompatible elastomers, flame retardants, slip agents, antiblocking agents, antioxidants, light stabilizers, crystal nucleating agents, and tackifiers.

[0088] When an exterior material includes an adhesive resin layer 15 and a sealant layer 16 like the exterior material 10, resin compositions for forming each layer may be prepared and laminated by the T-die method or the inflation method, or one layer may be formed and then another layer may be extruded thereon, or each layer may be produced by the T-die method or the inflation method and then laminated by bonding them together with an adhesive. From the viewpoint of interfacial adhesion, an adhesive containing an acid-modified polypropylene and a curing agent (such as isocyanate) may be used as the adhesive used.

[0089] The resins in the adhesive resin layer 15 and the sealant layer 16 can be analyzed by known analytical methods such as IR, NMR, various mass spectrometry, X-ray analysis, Raman spectroscopy, GPC, DSC, and DMA.

[0090] Although the preferred embodiment of the exterior material for an electricity storage device of the present embodiment has been described in detail above, the present disclosure is not limited to the specific embodiment described above.

[0091] For example, while FIG. 1 shows an exterior material having corrosion prevention treatment layers 14a, 14b on both sides of the barrier layer 13, the exterior material may have only one of the corrosion prevention treatment layers 14a, 14b, or may not have the corrosion prevention treatment layers 14a, 14b.

[0092] FIG. 1 shows a case in which the barrier layer 13 and the sealant layer 16 are laminated using an adhesive resin layer 15, but the barrier layer 13 and the sealant layer 16 may also be laminated using a second adhesive layer 12b, as in the exterior material 20 for an electricity storage device shown in FIG. 2.

[0093] <Second adhesive layer> Here, the second adhesive layer 12b will be described. The second adhesive layer 12b is a layer that bonds the barrier layer 13 and the sealant layer 16. For the second adhesive layer 12b, a general adhesive for bonding the barrier layer 13 and the sealant layer 16 can be used.

[0094] When a corrosion prevention treatment layer 14b is provided on the barrier layer 13, and the second corrosion prevention treatment layer 14b has a layer containing at least one polymer selected from the group consisting of the above-mentioned cationic polymers and anionic polymers, the second adhesive layer 12b is preferably a layer containing a compound (hereinafter also referred to as a "reactive compound") that is reactive with the above-mentioned polymer contained in the second corrosion prevention treatment layer 14b.

[0095] For example, when the second corrosion prevention treatment layer 14b contains a cationic polymer, the second adhesive layer 12b preferably contains a compound reactive with the cationic polymer. When the second corrosion prevention treatment layer 14b contains an anionic polymer, the second adhesive layer 12b preferably contains a compound reactive with the anionic polymer. In addition, when the second corrosion prevention treatment layer 14b contains a cationic polymer and an anionic polymer, the second adhesive layer 12b preferably contains a compound reactive with the cationic polymer and a compound reactive with the anionic polymer. However, the second adhesive layer 12b does not necessarily need to contain the above two types of compounds, and may contain a compound reactive with both the cationic polymer and the anionic polymer. Here, "reactive" means forming a covalent bond with the cationic polymer or the anionic polymer. In addition, the second adhesive layer 12b may further contain an acid-modified polyolefin resin.

[0096] The compound reactive with the cationic polymer may be at least one compound selected from the group consisting of a polyfunctional isocyanate compound, a glycidyl compound, a compound having a carboxy group, and a compound having an oxazoline group.

[0097] Examples of the polyfunctional isocyanate compound, glycidyl compound, compound having a carboxy group, and compound having an oxazoline group include the polyfunctional isocyanate compound, glycidyl compound, compound having a carboxy group, and compound having an oxazoline group, which are exemplified above as crosslinking agents for forming a crosslinked structure from a cationic polymer. Among these, the polyfunctional isocyanate compound is preferred in terms of high reactivity with the cationic polymer and ease of forming a crosslinked structure.

[0098] The compound reactive with an anionic polymer may be at least one compound selected from the group consisting of glycidyl compounds and compounds having an oxazoline group. Examples of the glycidyl compound and the compound having an oxazoline group include the glycidyl compounds and the compounds having an oxazoline group exemplified above as crosslinking agents for forming a crosslinked structure from a cationic polymer. Among these, the glycidyl compound is preferred because of its high reactivity with an anionic polymer.

[0099] When the second adhesive layer 12b contains an acid-modified polyolefin resin, the reactive compound preferably also has a reactivity with the acidic groups in the acid-modified polyolefin resin (ie, forms a covalent bond with the acidic groups). This further enhances the adhesion to the second corrosion prevention treatment layer 14b. In addition, the acid-modified polyolefin resin has a crosslinked structure, and the solvent resistance of the exterior material 20 is further improved.

[0100] The content of the reactive compound is preferably from one equivalent to ten equivalents relative to the acidic groups in the acid-modified polyolefin resin. If the amount is equal to or more than 10 times, the reactive compound reacts sufficiently with the acid group in the acid-modified polyolefin resin. On the other hand, if the amount is more than 10 times, the crosslinking reaction with the acid-modified polyolefin resin is sufficiently saturated, so that there is a concern that unreacted matter remains and various performances may be reduced. Therefore, for example, the content of the reactive compound is preferably 5 to 20 parts by mass (solid content ratio) per 100 parts by mass of the acid-modified polyolefin resin.

[0101] The acid-modified polyolefin resin is a polyolefin resin to which an acidic group has been introduced. Examples of the acidic group include a carboxyl group, a sulfonic acid group, and an acid anhydride group, and maleic anhydride groups and (meth)acrylic acid groups are particularly preferred. For example, the acid-modified polyolefin resin may be the same as the modified polyolefin resin used in the sealant layer 16.

[0102] The second adhesive layer 12b may contain various additives such as a flame retardant, a slip agent, an antiblocking agent, an antioxidant, a light stabilizer, and a tackifier.

[0103] The second adhesive layer 12b may contain, for example, an acid-modified polyolefin and at least one curing agent selected from the group consisting of a polyfunctional isocyanate compound, a glycidyl compound, a compound having a carboxy group, a compound having an oxazoline group, and a carbodiimide compound, from the viewpoint of suppressing a decrease in heat seal strength when corrosive gases such as hydrogen sulfide or an electrolyte are involved and from the viewpoint of further suppressing a decrease in insulating properties. Examples of the carbodiimide compound include N,N'-di-o-toluylcarbodiimide, N,N'-diphenylcarbodiimide, N,N'-di-2,6-dimethylphenylcarbodiimide, N,N'-bis(2,6-diisopropylphenyl)carbodiimide, N,N'-dioctyldecylcarbodiimide, N-triyl-N'-cyclohexylcarbodiimide, N,N'-di-2,2-di-t-butylphenylcarbodiimide, N-triyl-N'-phenylcarbodiimide, N,N'-di-p-nitrophenylcarbodiimide, N,N'-di-p-aminophenylcarbodiimide, N,N'-di-p-hydroxyphenylcarbodiimide, N,N'-di-cyclohexylcarbodiimide, and N,N'-di-p-toluylcarbodiimide.

[0104] In addition, as the adhesive for forming the second adhesive layer 12b, for example, a polyurethane adhesive obtained by blending polyester polyol made of hydrogenated dimer fatty acid and diol with polyisocyanate can be used. Examples of the adhesive include polyurethane resins obtained by reacting a bifunctional or higher isocyanate compound with a base material such as polyester polyol, polyether polyol, acrylic polyol, or carbonate polyol, and epoxy resins obtained by reacting an amine compound with a base material having an epoxy group. These are preferable from the viewpoint of heat resistance.

[0105] The thickness of the second adhesive layer 12b is not particularly limited, but from the viewpoint of obtaining the desired adhesive strength, processability, and the like, it is preferably 1 to 10 μm, and more preferably 2 to 7 μm.

[0106] [Exterior material manufacturing method] Next, there will be described an example of a method for manufacturing the exterior packaging material 10 shown in Fig. 1. Note that the method for manufacturing the exterior packaging material 10 is not limited to the following method.

[0107] The manufacturing method of the exterior material 10 of this embodiment is roughly composed of the steps of providing corrosion prevention treatment layers 14a, 14b on the barrier layer 13, bonding the base material layer 11 and the barrier layer 13 together using the first adhesive layer 12a, further laminating an adhesive resin layer 15 and a sealant layer 16 on the surface of the barrier layer 13 facing the corrosion prevention treatment layer 14b to produce a laminate, and, if necessary, aging the obtained laminate.

[0108] (Laminating process of corrosion prevention treatment layer onto barrier layer) This step is a step of forming the corrosion prevention treatment layers 14a, 14b on the barrier layer 13. As described above, examples of the method include subjecting the barrier layer 13 to a degreasing treatment, a hydrothermal conversion treatment, an anodizing treatment, or a chemical conversion treatment, or applying a coating agent having corrosion prevention properties.

[0109] Furthermore, when the corrosion prevention treatment layers 14a, 14b are multiple layers, for example, a coating liquid (coating agent) constituting the lower corrosion prevention treatment layer (barrier layer 13 side) may be applied to the barrier layer 13 and baked to form a first layer, and then a coating liquid (coating agent) constituting the upper corrosion prevention treatment layer may be applied to the first layer and baked to form a second layer.

[0110] The degreasing treatment may be performed by spraying or immersion. The hydrothermal conversion treatment and anodizing treatment may be performed by immersion. The chemical conversion treatment may be performed by an appropriate method such as immersion, spraying, or coating, depending on the type of chemical conversion treatment.

[0111] Regarding the coating method of the coating agent having corrosion prevention properties, various methods such as gravure coating, reverse coating, roll coating, bar coating, etc. can be used.

[0112] As described above, the various treatments for the barrier layer 13 may be performed on either one or both sides of the metal foil, but in the case of one-sided treatment, the treated side is preferably the side on which the sealant layer 16 is laminated. If required, the surface of the base layer 11 may also be subjected to the above treatments.

[0113] The amount of coating agent applied to form the first layer and the second layer is 0.005 to 0.200 g / m 2 It is preferable that the thickness is 0.010 to 0.100 g / m 2 It is more preferable that:

[0114] Furthermore, when dry curing is required, it can be performed at a base material temperature in the range of 60 to 300° C. depending on the drying conditions of the corrosion prevention treatment layers 14a and 14b used.

[0115] (Laminating process of substrate layer and barrier layer) This step is a step of bonding the barrier layer 13 provided with the anti-corrosion treatment layers 14a and 14b to the base material layer 11 via the first adhesive layer 12a. The base material layer 11 is bonded to the surface of the barrier layer 13 facing the anti-corrosion treatment layer 14a. The lamination may be performed by dry lamination, non-solvent lamination, wet lamination or the like, and the two are bonded together using the material constituting the first adhesive layer 12a described above. The first adhesive layer 12a has a dry coating amount of preferably 1 to 10 g / m 2 More preferably, the range is 2 to 7 g / m 2 It is set within the range.

[0116] (Laminating process of adhesive resin layer and sealant layer) The step of laminating the adhesive resin layer and the sealant layer is a step of forming an adhesive resin layer 15 and a sealant layer 16 on the surface of the barrier layer 13 on the side of the corrosion prevention treatment layer 14b. As a method for this, there is a method in which the adhesive resin layer 15 is sandwiched together with the sealant layer 16 by using an extrusion laminator. Furthermore, lamination is also possible by a tandem lamination method in which the adhesive resin layer 15 and the sealant layer 16 are extruded, or a co-extrusion method. In forming the adhesive resin layer 15 and the sealant layer 16, for example, the components are mixed so as to satisfy the above-mentioned configurations of the adhesive resin layer 15 and the sealant layer 16. For forming the adhesive resin layer 15, a resin composition for forming an adhesive resin layer containing the above-mentioned components for the adhesive resin layer 15 is used. The sealant layer 16 is formed using a resin composition for forming a sealant layer, which contains the above-mentioned components of the sealant layer 16. At this time, the sealant layer 16 has an oxygen permeability of 1.0×10 at 100° C. -15 ~1.0×10 -13 [(mol m) / (m 2 For this purpose, for example, the types of base resin (A) and additive (B) contained in the sealant layer 16 may be appropriately combined, the contents of the base resin (A) and additive (B) may be appropriately selected, and the crystallization temperature, melting temperature, MFR, and the like of the sealant layer 16 may be adjusted.

[0117] The process of laminating the adhesive resin layer and the sealant layer produces a laminate in which the layers are laminated in the following order: base layer 11 / first adhesive layer 12a / first corrosion prevention treatment layer 14a / barrier layer 13 / second corrosion prevention treatment layer 14b / adhesive resin layer 15 / sealant layer 16, as shown in FIG. 1.

[0118] The adhesive resin layer 15 may be laminated by directly extruding the materials dry-blended to have the above-mentioned material composition using an extrusion laminator. Alternatively, the adhesive resin layer 15 may be laminated by extruding the granulated material, which has been melt-blended in advance using a melt kneading device such as a single-screw extruder, a twin-screw extruder, or a Brabender mixer, using an extrusion laminator.

[0119] The sealant layer 16 may be laminated by directly extruding, with an extrusion laminator, a material obtained by dry blending the components of the resin composition for forming a sealant layer. Alternatively, the adhesive resin layer 15 and the sealant layer 16 may be laminated by a tandem lamination method in which the adhesive resin layer 15 and the sealant layer 16 are extruded with an extrusion laminator using a granulated product obtained by previously melt blending with a melt kneading device such as a single screw extruder, a twin screw extruder, or a Brabender mixer, or by a co-extrusion method. Alternatively, the adhesive resin layer 15 and the sealant layer 16 may be formed in advance as a cast film using a resin composition for forming a sealant layer, and then laminated by a method in which the sealant layer is sand-laminated together with the adhesive resin. From the viewpoint of productivity, the forming speed (processing speed) of the adhesive resin layer 15 and the sealant layer 16 can be, for example, 80 m / min or more.

[0120] (Aging process) The aging treatment step is a step of aging (curing) the laminate. By aging the laminate, it is possible to promote adhesion between the base layer 11 / first adhesive layer 12a / first corrosion prevention treatment layer 14a / barrier layer 13 and between the barrier layer 13 / second corrosion prevention treatment layer 14b / second adhesive layer 12b / sealant layer 16. The aging temperature may be 80° C. or more, 100° C. or more, or 120° C. or more, and may be 140° C. or less, 150° C. or less, or 160° C. or less. The aging time may be 1 hour or more, 2 hours or more, or 3 hours or more, and may be 24 hours or less, 48 ​​hours or less, or 72 hours or less.

[0121] In this manner, the exterior material 10 of the present embodiment as shown in FIG. 1 can be manufactured.

[0122] Next, a description will be given of an example of a method for manufacturing the exterior material 20 shown in Fig. 2. Note that the method for manufacturing the exterior material 20 is not limited to the following method.

[0123] The manufacturing method of the exterior material 20 of this embodiment is roughly composed of the steps of providing corrosion prevention treatment layers 14a, 14b on the barrier layer 13, bonding the base material layer 11 and the barrier layer 13 together using the first adhesive layer 12a, bonding the sealant layer 16 to the corrosion prevention treatment layer 14b side of the barrier layer 13 via the second adhesive layer 12b to obtain a laminate, and, if necessary, subjecting the obtained laminate to an aging treatment. The steps up to the step of bonding the base layer 11 and the barrier layer 13 with the first adhesive layer 12a can be performed in the same manner as in the above-mentioned method for producing the exterior material 10. The step of subjecting the obtained laminate to an aging treatment can be performed in the same manner as in the above-mentioned method for producing the exterior material 10.

[0124] (Lamination process of second adhesive layer and sealant layer) The lamination step of the second adhesive layer and sealant layer is a step of laminating the sealant layer 16 to the corrosion prevention treatment layer 14b side of the barrier layer 13 via the second adhesive layer 12b to obtain a laminate. The lamination method may be a wet process or a dry lamination.

[0125] In the case of a wet process, a solution or dispersion of the adhesive that constitutes the second adhesive layer 12b is applied onto the corrosion prevention treatment layer 14b, and the solvent is evaporated at a predetermined temperature to form a dry film, or after the dry film is formed, a baking process is performed as necessary. Thereafter, a sealant layer 16 is laminated to produce an exterior material 20. The coating method may be any of the various coating methods exemplified above. The preferred dry coating amount of the second adhesive layer 12b is the same as that of the first adhesive layer 12a.

[0126] In this case, the sealant layer 16 can be produced, for example, by a melt extrusion molding machine using a resin composition for forming a sealant layer containing the above-mentioned base resin (A) and additive (B). In the melt extrusion molding machine, the processing speed can be set to 80 m / min or more from the viewpoint of productivity.

[0127] The exterior material for an electricity storage device according to the present disclosure can also be used as an exterior material for electricity storage devices such as secondary batteries, such as lithium ion batteries, nickel-metal hydride batteries, and lead-acid batteries, and electrochemical capacitors, such as electric double layer capacitors. However, the exterior material for an electricity storage device according to the present disclosure can be particularly suitably used as an exterior material for an electricity storage device formed of an all-solid-state battery. The exterior material for an electric storage device can have excellent scratch resistance, so that unevenness is unlikely to form on the surface of the sealant layer. Therefore, when the exterior material for an electric storage device is used as an exterior material for an all-solid-state battery including an electric storage element, and the electric storage element is pressurized through the exterior material, the presence of areas where the pressure is high and areas where the pressure is low on the pressurized surface of the electric storage element is suppressed, and the pressurized surface of the electric storage element is uniformly pressurized. As a result, the all-solid-state battery can be operated efficiently.

[0128] [Electricity storage device] Next, an embodiment of the electricity storage device according to the present disclosure will be described. Fig. 3 is a perspective view showing an electricity storage device according to an embodiment of the present disclosure. As shown in Fig. 3, an all-solid-state battery 50 as an electricity storage device includes an electricity storage element 52, two metal terminals (current extraction terminals) 53 for extracting current from the electricity storage element 52 to the outside, and an exterior bag 54 for housing the electricity storage element 52 in an airtight state. The exterior bag 54 has the exterior material 10 according to the present embodiment described above, and is used as a container for housing the energy storage element 52. In the exterior material 10, the base material layer 11 is the outermost layer, and the sealant layer 16 is the innermost layer. That is, the exterior bag 54 can house the energy storage element 52 inside by folding one exterior material 10 in half and heat-sealing the peripheral portions, or by stacking two exterior materials 10 and heat-sealing the peripheral portions, so that the base material layer 11 is on the outside of the all-solid-state battery 50 and the sealant layer 16 is on the inside of the all-solid-state battery 50. Metal terminal 53 is sandwiched by exterior bag 54 with sealant layer 16 on the inside. Metal terminal 53 may be sandwiched by exterior bag 54 via tab sealant. Metal terminal 53 is a part of the current collector taken out to the outside of exterior material 10, and is made of metal foil such as copper foil or aluminum foil.

[0129] The energy storage element 52 has a pair of electrodes and a solid electrolyte sandwiched between the pair of electrodes. One of the pair of electrodes is a positive electrode, and the other is a negative electrode. Examples of the solid electrolyte include a sulfide-based solid electrolyte and an oxide-based solid electrolyte.

[0130] According to the all-solid-state battery 50, the exterior material 10 can have excellent scratch resistance, so that unevenness is unlikely to form on the surface of the sealant layer 16. Therefore, when the exterior material 10 is used as the exterior material 10 of the all-solid-state battery 50 including the electric storage element 52 and the electric storage element 52 is pressurized through the exterior material 10, the presence of a portion where the pressure is high and a portion where the pressure is low on the pressurized surface of the electric storage element 52 is suppressed, and the pressurized surface of the electric storage element 52 is uniformly pressurized. Therefore, the all-solid-state battery 50 can improve the uniformity of the resistance at the interface between the electrode and the solid electrolyte in the electric storage element 52. As a result, the all-solid-state battery 50 can be operated efficiently.

[0131] In the all-solid-state battery 50, the exterior bag 54 may have an exterior material 20 instead of the exterior material 10.

[0132] Furthermore, instead of the all-solid-state battery 50, it is also possible to use, as the power storage device, secondary batteries such as lithium ion batteries, nickel-metal hydride batteries, and lead-acid batteries, as well as electrochemical capacitors such as electric double-layer capacitors, semi-solid batteries, and the like. EXAMPLES

[0133] The present disclosure will be specifically described below based on examples, but the present disclosure is not limited to the following examples.

[0134] [Materials used] The materials used for the base layer, the first adhesive layer, the second adhesive layer, the first corrosion prevention treatment layer forming material, the second corrosion prevention treatment layer forming material and the barrier layer are as follows.

[0135] <Base material layer> PET: Polyethylene terephthalate film (thickness 25 μm) with corona treatment on one side

[0136] <First adhesive layer (mass per unit area: 4.0 g / m 2 ) for forming adhesives> An adhesive (first adhesive) prepared by mixing polyester polyol (manufactured by Showa Denko Materials Co., Ltd., product name: Teslac 2505-63, hydroxyl value: 7 to 11 mgKOH / g) and a nurate of isophorone diisocyanate (manufactured by Mitsui Chemicals, Inc., product name: Takenate 600) so that the NCO / OH ratio is 20.0, and diluting with ethyl acetate to a solid content of 26 mass%.

[0137] <Second adhesive layer (mass per unit area 3.0 g / m 2 ) for forming adhesives> An adhesive (second adhesive) containing 10 parts by mass (solid content ratio) of a polyisocyanate compound with an isocyanurate structure for 100 parts by mass of acid-modified polyolefin resin dissolved in toluene.

[0138] <Material for forming first corrosion prevention treatment layer and material for forming second corrosion prevention treatment layer> The first corrosion prevention treatment layer forming material (substrate layer side) and the second corrosion prevention treatment layer forming material (sealant layer side) are as follows (CL-1) and (CL-2). (CL-1): Sodium polyphosphate-stabilized cerium oxide sol adjusted to a solid content of 10% by mass using distilled water as a solvent. The sodium polyphosphate-stabilized cerium oxide sol was obtained by mixing 100 parts by mass of cerium oxide with 10 parts by mass of sodium salt of phosphoric acid. (CL-2): A composition prepared by using distilled water as a solvent and adjusting the solid content concentration to 5% by mass. In the above composition, the ratio of polyallylamine (manufactured by Nitto Boseki Co., Ltd.) to polyglycerol polyglycidyl ether (manufactured by Nagase ChemteX Corporation) was 90:10 (mass ratio).

[0139] <Barrier layer (thickness 40 μm)> AL: Annealed and degreased soft aluminum foil (manufactured by Toyo Aluminum, "8079 material")

[0140] <Adhesive resin layer> Maleic anhydride modified homopolypropylene (Oxygen permeability at 100°C: 1.8×10 -14 [(mol m) / (m 2 ·s·Pa)], crystallization temperature: 120℃, melting temperature: 162℃)

[0141] <Sealant layer> The base resin (A), additive (B) and film used in the sealant layer are as shown in the following Table 1. In the following Table 1, "PP" stands for "polypropylene" and "PE" stands for "polyethylene."

[0142] [Table 1]

[0143] [Creating exterior materials] Example 1 First, a first and a second corrosion prevention treatment layer were provided on the barrier layer by the following procedure. That is, (CL-1) was applied to both sides of the barrier layer at a dry coating amount of 70 mg / m 2 The layer was then coated by microgravure coating so that the thickness of the layer was 200 mm, and the layer was baked at 200° C. in a drying unit. Next, (CL-2) was applied to the layer obtained in a dry coating amount of 20 mg / m 2By applying the coating by microgravure coating so that the above-mentioned coating conditions were satisfied, a composite layer consisting of (CL-1) and (CL-2) was formed as the first and second corrosion prevention treatment layers. This composite layer exhibits corrosion prevention performance by combining the two types of materials, (CL-1) and (CL-2).

[0144] Next, the first anti-corrosion treatment layer side of the barrier layer provided with the first anti-corrosion treatment layer and the second anti-corrosion treatment layer was attached to the base layer by dry lamination using the first adhesive to form the first adhesive layer, to obtain a first laminate (base layer / first adhesive layer / first anti-corrosion treatment layer / barrier layer / second anti-corrosion treatment layer). Specifically, the first adhesive was applied to the surface of the barrier layer facing the first anti-corrosion treatment layer so that the thickness after curing was 5 μm, and the first adhesive was dried at 80° C. for 1 minute, and then laminated with the base layer and aged at 80° C. for 120 hours to obtain a first laminate.

[0145] Next, the first laminate was set on the unwinding section of the extrusion laminator. An adhesive resin layer and a sealant layer were laminated in this order on the second corrosion prevention treatment layer of the first laminate by co-extrusion from a T-die under processing conditions of 270°C and 80m / min, to obtain an exterior material (a laminate of a substrate layer / first adhesive layer / first corrosion prevention treatment layer / barrier layer / second corrosion prevention treatment layer / adhesive resin layer / sealant layer). At this time, the thicknesses of the adhesive resin layer and the sealant layer were 25μm and 55μm, respectively. At this time, for the sealant layer, a resin composition for forming a sealant layer was prepared in advance by dry-blending the base resin (A) and additive (B) shown in Table 2 to have the content shown in Table 2, and this resin composition was used.

[0146] (Examples 2 to 16 and Comparative Examples 1 to 2) Except for setting the oxygen permeability and composition of the sealant layer as shown in Table 2, the same procedure as in Example 1 was followed to prepare an exterior material.

[0147] (Example 17) In the same manner as in Example 1, a first laminate (substrate layer / first adhesive layer / first corrosion prevention treatment layer / barrier layer / second corrosion prevention treatment layer) was obtained. Next, a sealant layer having the oxygen permeability and composition shown in Table 2 was attached to the second corrosion prevention treatment layer of the first laminate using a second adhesive to form a second adhesive layer by dry lamination. In this case, the first laminate and the sealant layer were laminated by applying the second adhesive onto the second corrosion prevention treatment layer so that the thickness after drying would be 3 μm, drying it at 80°C for 1 minute, laminating it with the sealant layer, and aging it at 120°C for 3 hours. In this manner, an exterior material (a laminate of substrate layer / first adhesive layer / first corrosion prevention treatment layer / barrier layer / second corrosion prevention treatment layer / second adhesive layer / sealant layer) was produced.

[0148] Comparative Example 3 In the same manner as in Example 1, a first laminate (substrate layer / first adhesive layer / first corrosion prevention treatment layer / barrier layer / second corrosion prevention treatment layer) was obtained. Next, a PET film shown in Table 2 was attached as a sealant layer onto the second corrosion prevention treatment layer of the first laminate using a second adhesive to form a second adhesive layer by dry lamination. In this case, the first laminate and the sealant layer were laminated by applying an adhesive for forming a second adhesive layer onto the second corrosion prevention treatment layer so that the thickness after drying would be 3 μm, drying at 80°C for 1 minute, laminating it with the sealant layer, and aging it at 120°C for 3 hours. In this manner, an exterior material (substrate layer / first adhesive layer / first corrosion prevention treatment layer / barrier layer / second corrosion prevention treatment layer / second adhesive layer / sealant layer) was produced.

[0149] [Measurement method] <Oxygen permeability> The oxygen permeability of the sealant layer was measured as follows. First, the resin composition for forming a sealant layer was heated and melted at 200° C. to prepare a measurement sheet having a thickness of 80 μm. Next, a differential pressure type gas permeability measuring device was prepared. As the differential pressure type gas permeability measuring device, a device equipped with a first gas pipe and a second gas pipe equipped with a valve and a pressure sensor, and a ceramic electric tubular furnace (model: ARF-50K, manufactured by Asahi Rika Seisakusho Co., Ltd.) having a heater was used. Then, using this differential pressure type gas permeability measuring device, the oxygen permeability of the measurement sheet was measured by a differential pressure method. Specifically, the measurement sheet was placed so as to be sandwiched between the end face of the first gas pipe and the end face of the second gas pipe, and kept at 100°C in the ceramic electric tubular furnace, and oxygen gas (purity: 99.7% or more) was supplied to the first gas pipe on one side of the measurement sheet so that the pressure difference between the first gas pipe and the second gas pipe was 0.1 MPa, and the oxygen permeability was measured by measuring the change over time in the pressure of the oxygen gas in the second gas pipe that permeates the measurement sheet. The results are shown in Table 2.

[0150] <Crystallization temperature and melting temperature> The crystallization temperatures and melting temperatures of the base resin (A), the additive (B) and the film were measured as follows. First, 5 mg of a sample made of the same material as the base resin (A), additive (B), or film was prepared. The sample was then placed in a measurement container and set in a differential scanning calorimeter (DSC) measurement device to measure the crystallization temperature and melting temperature in accordance with JIS K7121-1987. The measurement was performed twice by increasing the temperature from 23° C. to 210° C. at a rate of 10° C. / min, and then decreasing the temperature from 210° C. to 23° C. at a rate of 10° C. / min. The crystallization temperature was determined as the peak top temperature of the crystallization peak during the first run when the temperature was decreased, and the melting temperature was determined as the peak top temperature of the melting peak during the second run when the temperature was increased. The results are shown in Table 1. Regarding the melting temperature, since the first run was dependent on the crystalline state at the time of measurement, the measurement was performed in a second run after resetting the crystallinity.

[0151] <mfr> The MFR (melt flow rate) of the base resin (A), the additive (B) and the film was measured as follows. First, a sample was prepared, which was made of the same material as the base resin (A), additive (B) or film. The MFR (unit: g / 10 min) of this sample was measured under conditions of 230° C. and a load of 2.16 kg in accordance with JIS K7210. The results are shown in Table 1.

[0152] [Scratch resistance evaluation] A pencil hardness test was carried out on the exterior packaging materials obtained in Examples 1 to 17 and Comparative Examples 1 to 3. Specifically, a pencil hardness tester specified in JIS K 5600 was used to check how the sealant layer of the exterior packaging material was scratched, and the pencil hardness was measured. Then, depending on the pencil hardness results, the scratch resistance was evaluated based on the following evaluation criteria. The results are shown in Table 2. [Evaluation Criteria] S: Pencil hardness is 5H or higher A: When the pencil hardness is between 3H and 5H B: Pencil hardness is 2H or more but less than 3H C: Pencil hardness is H or more but less than 2H D: Pencil hardness is less than H

[0153] [Table 2]

[0154] From the results shown in Table 2, the scratch resistance of the exterior packaging materials of Examples 1 to 17 was evaluated as "S," "A," "B," or "C." In contrast, the scratch resistance of the exterior packaging materials of Comparative Examples 1 to 3 was evaluated as "D." From the above, it has been confirmed that the exterior material of the present disclosure can have excellent scratch resistance. [Explanation of symbols]

[0155] 10, 20...outer packaging material, 11...substrate layer, 13...barrier layer, 15...adhesive resin layer, 16...sealant layer, 50...all-solid-state battery (energy storage device), 52...energy storage element, 54...outer packaging bag.< / mfr>

Claims

1. An exterior material for an electricity storage device used in an electricity storage device, At least a base layer, a barrier layer, and a sealant layer are provided in this order, The sealant layer has an oxygen permeability of 1.0×10 at 100° C. －１５ ~1.0 x 10 －１３ [(mol・m) / (m ２ s Pa)], The exterior packaging material for an electricity storage device, wherein the sealant layer contains a base resin (A) made of a polypropylene-based resin.

2. An exterior material for an electricity storage device as described in claim 1, wherein the polypropylene-based resin includes at least one of homopolypropylene and block polypropylene.

3. The exterior material for an electricity storage device according to claim 1, wherein the polypropylene-based resin has a crystallization temperature of 100 to 120°C and a melting temperature of 155 to 168°C.

4. The exterior packaging material for an electricity storage device according to claim 1, wherein the melting temperature-crystallization temperature of the base resin (A) is 40 to 65°C.

5. The exterior material for an electrical storage device according to claim 1, wherein the proportion of the base resin (A) in the sealant layer is 80 to 100 mass %.

6. The packaging material for an electricity storage device according to any one of claims 1 to 5, wherein the electricity storage device is an all-solid-state battery.

7. A storage element; an outer bag that houses the energy storage element, An electricity storage device, wherein the outer packaging bag comprises the packaging material according to any one of claims 1 to 5.

8. The electricity storage device according to claim 7 , which is an all-solid-state battery.

Images