Adhesive, exterior material for power storage device, exterior case for power storage device, and power storage device

Abstract

To provide an adhesive which enables manufacture of an exterior material for a power storage device having good moldability.SOLUTION: An adhesive contains an adhesive component, has shear adhesive strength of 0.7 MPa or more, and is used for forming an adhesive layer between a base material layer and a barrier layer when an exterior material for a power storage device is manufactured.SELECTED DRAWING: None

Description

Technical Field

[0001] The present disclosure relates to an adhesive, an exterior material for a power storage device, an exterior case for a power storage device, and a power storage device.

Background Art

[0002] In recent years, with the thinning and weight reduction of mobile electric devices such as smartphones and tablet terminals, as an exterior material for power storage devices such as lithium-ion secondary batteries, lithium polymer secondary batteries, lithium-ion capacitors, and electric double layer capacitors mounted on these devices, instead of conventional metal cans, a laminate composed of a heat-resistant resin layer / adhesive layer / metal foil layer / adhesive layer / thermoplastic resin layer (inner sealant layer) is used. In addition, power sources for electric vehicles, large power sources for power storage applications, capacitors, etc. are also increasingly being externally packaged with laminates (exterior materials) having the above configuration. By performing bulging molding or deep drawing molding on the laminate, it is formed into a three-dimensional shape such as a substantially rectangular parallelepiped shape. By forming such a three-dimensional shape, a storage space for accommodating the main body of the power storage device can be secured.

[0003] In order to be formed into such a three-dimensional shape in good condition without pinholes, breakage, etc., it is required to improve the slipperiness of the surface of the inner sealant layer. As a method for improving the slipperiness of the surface of the inner sealant layer, adding an antiblocking agent to the inner sealant layer can be mentioned. However, if an excessive amount of antiblocking agent is added to the inner sealant layer, the inner sealant layer is likely to become cloudy, and due to the cloudiness of the sealant layer, there is a problem that it is easy to overlook delamination (delamination) in the exterior material during quality inspection.

[0004] In Patent Document 1, an exterior material for a power storage device has been proposed that can ensure good slidability during molding, ensure good moldability, and suppress cloudiness in the exterior material.

Prior Art Documents

Patent Documents

[0005] Patent Document 1 Japanese Patent No. 6936093 SUMMARY OF THE INVENTION PROBLEMS TO BE SOLVED BY THE INVENTION

[0006] For example, a power storage device is obtained by joining an inner sealant layer by heat sealing with a power storage device main body portion accommodated in an outer case obtained by molding an exterior material for a power storage device as described in Patent Document 1. The exterior material for a power storage device is molded by deep drawing molding, overhanging molding, etc. From the viewpoints of expanding applications, productivity of the power storage device, etc., it is desirable to increase the molding depth and improve the moldability while suppressing the occurrence of pinholes, cracks, etc.

[0007] An object of the present disclosure is to provide an exterior material for a power storage device that can obtain high moldability, an outer case for a power storage device using the same, and a power storage device. MEANS FOR SOLVING THE PROBLEMS

[0008] Specific means for achieving the above problems are as follows. <1> An adhesive for forming an adhesive layer between a base material layer and a barrier layer in the production of an exterior material for a power storage device, which contains an adhesive component and has a shear adhesive strength of 0.7 MPa or more. <2> An adhesive containing an adhesive component and an additive, and having a shear adhesive strength increase rate of 20% or more with respect to a comparative adhesive having the same composition except for not containing the additive, for forming an adhesive layer between a base material layer and a barrier layer in the production of an exterior material for a power storage device. <3> The adhesive according to <1> or <2>, wherein the adhesive component contains at least one selected from the group consisting of polyester and polyurethane. <4> The adhesive according to any one of <1> to <3>, further containing a metal salt containing an amino group and a carbonyl group. <5> The adhesive according to any one of <2> to <4>, wherein the additive contains a metal salt containing an amino group and a carbonyl group. <6> The adhesive according to <4>, wherein the content of the metal salt is 0.5% by mass to 4% by mass based on the solid content of the adhesive. <7> The adhesive according to <5>, wherein the content of the metal salt is 0.5% by mass to 4% by mass based on the solid content of the adhesive. <8> An exterior material for a power storage device, in which a base material layer, an adhesive layer formed by the adhesive according to any one of <1> to <7>, a barrier layer, and a sealant layer are laminated in this order. <9> A step of applying the adhesive according to any one of <1> to <7> to the base material layer or the barrier layer, A step of laminating the barrier layer or the base material layer on the applied adhesive, A method for manufacturing an exterior material for a power storage device, comprising: <10> An exterior case for a power storage device, which is a molded body of the exterior material for a power storage device according to <8>. <11> A power storage device main body, An exterior member that houses the power storage device main body and includes the exterior material for a power storage device according to <10>. A power storage device comprising:

Advantages of the Invention

[0009] According to the present disclosure, it is possible to provide an exterior material for a power storage device having high moldability, an exterior case for a power storage device using the same, and a power storage device.

Brief Description of the Drawings

[0010]

Figure 1

Figure 2

Figure 3

Modes for Carrying Out the Invention

[0011] Hereinafter, the present disclosure will be described in detail. However, the present disclosure is not limited to the following embodiments. In the following embodiments, the components (including element steps, etc.) are not essential unless otherwise specified. The same applies to numerical values and their ranges, which do not limit the present disclosure.

[0012] In the present disclosure, the term "step" includes not only a step independent of other steps but also a step that cannot be clearly distinguished from other steps as long as the purpose of the step is achieved. In the numerical range indicated by "~" in the present disclosure, the numerical values described before and after "~" are included as the minimum value and the maximum value, respectively. In the numerical ranges described step by step in the present disclosure, the upper limit value or the lower limit value described in one numerical range may be replaced with the upper limit value or the lower limit value of the numerical range described in other step-by-step descriptions. Also, in the numerical ranges described in the present disclosure, the upper limit value or the lower limit value of the numerical range may be replaced with the value shown in the examples. In the present disclosure, each component may contain a plurality of corresponding substances. When there are a plurality of substances corresponding to each component in the composition, the content rate or content of each component means the total content rate or content of the plurality of substances present in the composition, unless otherwise specified. In the present disclosure, the particles corresponding to each component may contain a plurality of types of particles. When there are a plurality of types of particles corresponding to each component in the composition, the particle diameter of each component means a value for the mixture of the plurality of types of particles present in the composition, unless otherwise specified.

[0013] Hereinafter, the adhesive of the present disclosure will be described, including the adhesive of the first embodiment, the adhesive of the second embodiment, or the adhesive of the third embodiment. Note that the adhesive of the present disclosure is not limited to the following embodiments. Also, within the scope where the effects of the present invention are achieved, the configurations of each embodiment may be combined.

[0014] <Adhesive> [First Embodiment] The adhesive according to the first embodiment of the present disclosure contains an adhesive component, has a shear adhesive strength of 0.7 MPa or more, and is used for forming an adhesive layer between a base material layer and a barrier layer when manufacturing an exterior material for a power storage device.

[0015] Since the shear adhesive strength of the adhesive of the first embodiment is 0.7 MPa or more, when forming an exterior material for a power storage device by deep drawing molding, overhang molding, etc., generation of pinholes, cracks, etc. can be suppressed, and the molding depth can be increased to improve moldability. The reason for this is presumably that as the shear adhesive strength improves, the barrier layer follows the base material layer more during molding, making it less likely to be locally stretched and less likely to neck.

[0016] Preferably, the shear adhesive strength of the adhesive of the present disclosure is 0.75 MPa or more, and more preferably 0.8 MPa or more. The upper limit of the shear adhesive strength of the adhesive of the present disclosure is not particularly limited. The shear adhesive strength of the adhesive is measured by the method described in the examples. For example, it may be the shear adhesive strength of the adhesive when the base material layer is a nylon film and the barrier layer is an aluminum foil.

[0017] In the present disclosure, an exterior material for a power storage device is a member for manufacturing a power storage device by housing a power storage device main body. For example, the exterior material for a power storage device is a member in which a base material layer, an adhesive layer (also referred to as an outer adhesive layer) formed by the adhesive of the present disclosure, a barrier layer, and a sealant layer are laminated in this order, and an adhesive layer (also referred to as an inner adhesive layer) may be formed between the barrier layer and the sealant layer.

[0018] The adhesive of the present disclosure contains an adhesive component. The adhesive may be any of a chemical reaction type, a solvent evaporation type, a hot melt type, a hot press type, etc. Also, it may be a two-component curing adhesive (two-component adhesive), a one-component curing adhesive (one-component adhesive), or a resin without a curing reaction.

[0019] Examples of the adhesive component contained in the adhesive include polyesters such as polyethylene terephthalate, polybutylene terephthalate, polyethylene naphthalate, polybutylene naphthalate, polyethylene isophthalate, and copolyester; polyethers; polyurethanes; epoxy resins; phenolic resins; polyamides such as nylon 6, nylon 66, nylon 12, and copolyamide; polyolefin resins such as polyolefin, cyclic polyolefin, acid-modified polyolefin, and acid-modified cyclic polyolefin; polyvinyl acetate; cellulose; (meth)acrylic resins; polyimides; polycarbonates; amino resins such as urea resin and melamine resin; rubbers such as chloroprene rubber, nitrile rubber, and styrene-butadiene rubber; silicone resins; and the like. Examples of the adhesive component in the thermosetting adhesive include polyester resins, polyolefin resins, epoxy resins, (meth)acrylic resins, and the like. The adhesive component may be included alone or in combination of two or more.

[0020] The adhesive component contained in the adhesive preferably includes at least one selected from the group consisting of polyester and polyurethane.

[0021] The adhesive of the present disclosure preferably contains a metal salt containing an amino group and a carbonyl group (hereinafter, also referred to as a specific metal salt). By using the specific metal salt, the adhesiveness between the base material layer (for example, nylon film) and the barrier layer (for example, aluminum foil) of the adhesive tends to be improved. The specific metal salt may be included alone or in combination of two or more.

[0022] The specific metal salt preferably contains two or more amino groups and two or more carbonyl groups, and more preferably contains three amino groups and three carbonyl groups.

[0023] The specific metal salt may contain a ring structure, may contain an amino group and a carbonyl group in the ring structure, and may contain an isocyanuric ring.

[0024] The metals contained in the specific metal salt include zinc, titanium, chromium, manganese, iron, cobalt, copper, molybdenum, cadmium, aluminum, beryllium, magnesium, calcium, strontium, barium, etc. Among them, zinc is preferable.

[0025] Examples of the specific metal salt include zinc cyanurate, titanium cyanurate, chromium cyanurate, manganese cyanurate, iron cyanurate, cobalt cyanurate, copper cyanurate, molybdenum cyanurate, cadmium cyanurate, aluminum cyanurate, beryllium cyanurate, magnesium cyanurate, calcium cyanurate, strontium cyanurate, and barium cyanurate.

[0026] From the viewpoint of shear adhesion strength, the content of the specific metal salt is preferably 0.5% by mass to 4% by mass, more preferably 0.8% by mass to 3% by mass, and even more preferably 1% by mass to 2.5% by mass based on the solid content of the adhesive.

[0027] The adhesive of the present disclosure may contain other components. Examples of the other components include colorants, thermoplastic elastomers, tackifiers, fillers, etc. When a colorant is contained in the adhesive, an exterior material for a colored power storage device can be obtained. As the colorant, known ones such as pigments and dyes can be used. Further, the colorant may be contained alone or in combination of two or more.

[0028] [Second Embodiment] The adhesive according to the second embodiment of the present disclosure is an adhesive containing an adhesive component and an additive, and has a shear adhesion strength increase rate of 20% or more with respect to a comparative adhesive having the same composition except for not containing the additive, and is used for forming an adhesive layer between a base material layer and a barrier layer when manufacturing an exterior material for a power storage device.

[0029] The adhesive of the second embodiment has an increased shear adhesion strength rate of 20% or more with respect to the comparative adhesive, so the shear adhesion strength is improved. When forming the exterior material for the power storage device by deep drawing molding, overhanging molding, etc., the formability can be enhanced.

[0030] The increased rate of the shear adhesion strength with respect to the comparative adhesive is preferably 25% or more, and more preferably 30% or more. The upper limit of the increased rate of the shear adhesion strength with respect to the comparative adhesive is not particularly limited.

[0031] The preferred configuration of the adhesive component contained in the adhesive of the second embodiment is the same as the preferred configuration of the adhesive component contained in the adhesive of the first embodiment.

[0032] Examples of the additive contained in the adhesive of the second embodiment include the aforementioned specific metal salts, the aforementioned other components, etc. The adhesive preferably contains a specific metal salt as the aforementioned additive. From the viewpoint of the shear adhesion strength, the preferred content of the specific metal salt is preferably 0.5% by mass to 4% by mass, more preferably 0.8% by mass to 3% by mass, and even more preferably 1% by mass to 2.5% by mass with respect to the solid content of the adhesive.

[0033] [Third Embodiment] The adhesive of the third embodiment of the present disclosure contains an adhesive component and a metal salt (specific metal salt) containing an amino group and a carbonyl group, and the content of the specific metal salt is 0.5% by mass to 4% by mass with respect to the solid content of the adhesive.

[0034] In the adhesive of the third embodiment, the shear adhesion strength can be increased by adjusting the content of the specific metal salt. Thereby, the formability of the exterior material for the power storage device is improved.

[0035] The adhesive of the third embodiment may be used for forming the adhesive layer between the base material layer and the barrier layer when manufacturing the exterior material for the power storage device, or may be used for other applications.

[0036] The matters described in the first embodiment or the second embodiment may be appropriately combined with the adhesive of the third embodiment.

[0037] <Outer packaging material for power storage device> The outer packaging material for a power storage device of the present disclosure is a member in which a base material layer, an adhesive layer formed by the above-described adhesive of the present disclosure, a barrier layer, and a sealant layer are laminated in this order.

[0038] Hereinafter, the layer configuration of the outer packaging material for a power storage device will be described.

[0039] (Base material layer) The outer packaging material for a power storage device includes a base material layer. The base material layer is preferably formed of a heat-resistant resin layer. The heat-resistant resin is preferably a resin that does not melt at the heat-sealing temperature when heat-sealing the outer packaging material. The heat-resistant resin preferably has a high melting point. For example, it is preferably higher than the melting point of each layer included in the sealant layer, and preferably has a melting point 10°C or higher, more preferably 20°C or higher, than the melting point of the layer having the highest melting point among the layers included in the sealant layer.

[0040] Examples of the base material layer include polyamide films such as nylon films, and polyester films. These films may be stretched films. Examples of the stretched film include biaxially stretched polyamide films such as biaxially stretched nylon films, biaxially stretched polybutylene terephthalate (PBT) films, biaxially stretched polyethylene terephthalate (PET) films, and biaxially stretched polyethylene naphthalate (PEN) films. Examples of the nylon film include 6-nylon films, 6,6-nylon films, and MXD-nylon films.

[0041] The base material layer may be a single layer or a multi-layer composed of two or more layers. Examples of the multi-layer include a polyester film / polyamide film (e.g., PET film / nylon film). An adhesive layer may be formed between the polyester film and the polyamide film. The adhesive constituting the adhesive layer is not particularly limited, and examples include thermosetting adhesives, the adhesives of the present disclosure used for forming the outer adhesive layer described later, etc. The thermosetting adhesive is not particularly limited, and examples include polyurethane-based adhesives, poly(meth)acrylate-based adhesives, modified polypropylene-based adhesives, polyester-based adhesives, polyamide-based adhesives, olefin-based adhesives, epoxy-based adhesives, acrylic-based adhesives, etc.

[0042] The thickness of the base material layer may be 2 μm to 50 μm. For example, when the base material layer is a polyester film, its thickness may be 2 μm to 50 μm, and when the base material layer is a nylon film, its thickness may be 7 μm to 50 μm.

[0043] (Outer adhesive layer) An adhesive layer (also referred to as an outer adhesive layer) is provided between the base material layer and the barrier layer described later. The adhesive constituting the outer adhesive layer is the adhesive of the present disclosure described above, and may be the adhesive of the first embodiment, the adhesive of the second embodiment, or the adhesive of the third embodiment.

[0044] The thickness of the outer adhesive layer may be 1 μm to 7 μm. Among them, from the viewpoint of thinning and lightening the packaging material, the thickness of the outer adhesive layer is preferably 1 μm to 5 μm.

[0045] The outer adhesive layer may be a single layer or a multi-layer of two or more layers. In the case of a multi-layer, for example, a combination of an adhesive layer containing a colorant and an adhesive layer not containing a colorant may be used.

[0046] (Barrier layer) The exterior material for the power storage device includes a barrier layer. The barrier layer plays a role in imparting gas barrier properties to the exterior material to suppress the intrusion of oxygen, moisture, etc. The barrier layer is not particularly limited, and examples include metal foils, vapor deposition films, resin layers, etc. Examples of the vapor deposition film include metal vapor deposition films, inorganic oxide vapor deposition films, carbon-containing inorganic oxide vapor deposition films, etc. The metal foil is not particularly limited, and examples include aluminum foil, SUS foil (stainless steel foil), Cu foil, Ni foil, Ti foil, etc. Among them, aluminum foil and SUS foil (stainless steel foil) are preferred. Examples of the resin used for the resin layer include fluorine-containing resins, ethylene vinyl alcohol copolymers, etc. Examples of the fluorine-containing resin include polyvinylidene chloride, polymers mainly composed of chlorotrifluoroethylene (CTFE), polymers mainly composed of tetrafluoroethylene (TFE), polymers having a fluoroalkyl group, polymers mainly composed of fluoroalkyl units, etc.

[0047] The barrier layer may be a single layer or a multilayer of two or more layers. In the case of a multilayer, it may be a laminate of the same type of layer or a laminate of different types of layers. Examples of the laminate of different types of layers include a combination of a vapor deposition film and a resin layer.

[0048] From the viewpoints of suppressing the generation of pinholes during rolling and formability, the thickness of the barrier layer may be 5 μm to 120 μm, or may be 10 μm to 80 μm.

[0049] The metal foil may be subjected to chemical conversion treatment on at least one of the surface on the substrate layer side and the surface on the adhesive layer side, and for example, may have a corrosion prevention layer. By providing the corrosion prevention layer, corrosion of the metal foil surface by the contents (such as the electrolyte of the battery) can be suppressed. For example, the metal foil may be subjected to chemical conversion treatment to form a corrosion prevention layer by performing the following treatment. For example, on the surface of the degreased metal foil, 1) An aqueous solution of a mixture containing phosphoric acid, chromic acid, and at least one compound selected from the group consisting of metal salts of fluorides and non-metal salts of fluorides 2) Phosphoric acid, At least one resin selected from the group consisting of an acrylic resin, a chitosan derivative resin, and a phenolic resin, and at least one compound selected from the group consisting of chromic acid and chromium(III) salts, an aqueous solution of a mixture containing the same 3) Phosphoric acid, At least one resin selected from the group consisting of an acrylic resin, a chitosan derivative resin, and a phenolic resin, and at least one compound selected from the group consisting of chromic acid and chromium(III) salts, and at least one compound selected from the group consisting of a metal salt of fluoride and a non-metal salt of fluoride, an aqueous solution of a mixture containing the same After applying any of the aqueous solutions of 1) to 3) above and drying, a chemical conversion treatment is performed.

[0050] The chemical conversion film formed by the chemical conversion treatment has a chromium adhesion amount (per side) of 0.1 mg / m 2 ~50 mg / m 2 is preferable, and 2 mg / m 2 ~20 mg / m 2 is more preferable.

[0051] (Inner adhesive layer) An adhesive layer (also referred to as an inner adhesive layer) may be provided between the barrier layer and the sealant layer described later, and the barrier layer and the sealant layer may be integrated via the inner adhesive layer.

[0052] The adhesive constituting the inner adhesive layer is not particularly limited, and examples thereof include thermosetting adhesives and the adhesives of the present disclosure used for forming the outer adhesive layer described above. The thermosetting adhesive is not particularly limited, and examples thereof include olefin-based adhesives, epoxy-based adhesives, acrylic-based adhesives, and acid-modified polyolefin-based adhesives such as maleic anhydride-modified polypropylene.

[0053] The thickness of the inner adhesive layer may be 1 μm to 5 μm. Among them, from the viewpoints of thinning and weight reduction of the packaging material, the thickness of the inner adhesive layer is preferably 1 μm to 3 μm. When the inner adhesive layer is composed of an acid-modified polyolefin-based adhesive, the thickness of the inner adhesive layer may be 1 μm to 50 μm, or may be 10 μm to 50 μm.

[0054] (Sealant layer) The exterior material for a power storage device includes a sealant layer. The sealant layer is a layer that plays a role of imparting heat sealability to the exterior material. For example, the sealant layer may include one or more heat-sealable resin layers, and may include two or three heat-sealable resin layers.

[0055] The heat-sealable resin layer contains a heat-sealable resin, and may contain a lubricant, incompatible particles, and other components described later as necessary.

[0056] The heat-sealable resin is selected such that it melts at the heat-sealing temperature, and those having a melting point below the heat-sealing temperature are selected. The heat-sealable resin is not particularly limited as long as it has the above melting point, and is preferably at least one selected from the group consisting of polyethylene, polypropylene, olefin copolymers, acid-modified products thereof, and ionomers. "Polyethylene, polypropylene, olefin copolymers, acid-modified products thereof, and ionomers" are also referred to as "specific polyolefins".

[0057] Among the resins contained in the heat-sealable resin layer, the proportion of the specific polyolefin is preferably 50% by mass or more, more preferably 60% by mass or more, further preferably 70% by mass or more, particularly preferably 80% by mass or more, extremely preferably 90% by mass or more, and may be 95% by mass or more, may be 98% by mass or more, or may be 99% by mass or more.

[0058] The heat-sealable resin layer may be composed of a single heat-sealable resin, or may be composed of two or more heat-sealable resins. The plurality of heat-sealable resin layers contained in the sealant layer may each be composed of the same type of heat-sealable resin, or may be composed of different heat-sealable resins.

[0059] The heat-sealable resin layer in the sealant layer may further contain a lubricant. The lubricant is not particularly limited, and examples thereof include fatty acid amides. The fatty acid amide is not particularly limited, and examples thereof include saturated fatty acid amides, unsaturated fatty acid amides, substituted amides, methylol amides, saturated fatty acid bisamides, unsaturated fatty acid bisamides, fatty acid ester amides, aromatic bisamides, and the like.

[0060] The lubricant may be contained in any layer in the sealant layer, or may not be contained.

[0061] The heat-sealable resin layer in the sealant layer may further contain incompatible particles. The incompatible particles may be inorganic particles, organic particles, metal particles, composite particles thereof, or the like. From the viewpoint of suppressing deformation due to heat during heat melting, the incompatible particles are preferably inorganic particles, metal particles, or composite particles thereof. From the viewpoints of ensuring the insulation function of the sealant layer and weight reduction, the incompatible particles are preferably inorganic particles, organic particles, or composite particles thereof. From these comprehensive viewpoints, it is more preferable that the incompatible particles contain inorganic particles. The incompatible particles may be used alone or in combination of two or more.

[0062] Examples of the inorganic particles include inorganic oxide particles (such as silica particles, alumina particles, titanium oxide particles), inorganic carbonate particles (such as calcium carbonate particles, barium carbonate particles), inorganic silicate particles (such as aluminum silicate particles, talc particles, kaolin particles), and the like.

[0063] Examples of the organic particles include acrylic resin particles, polyolefin resin particles (such as polyethylene resin particles, polypropylene resin particles), polystyrene resin particles, and the like.

[0064] The incompatible particles may be contained in any layer in the sealant layer, or may not be contained. Also, the content rate of the incompatible particles may be changed in a plurality of heat-sealable resin layers.

[0065] The heat-sealable resin layer in the sealant layer may contain other components. Examples of other components include antioxidants, plasticizers, ultraviolet absorbers, fungicides, colorants (pigments, dyes, etc.), antistatic agents, rust preventives, moisture absorbers, oxygen absorbers, etc. The plasticizer is not particularly limited, and examples thereof include glycerin fatty acid ester monoglyceride, acetylated monoglyceride of glycerin fatty acid ester, organic acid monoglyceride of glycerin fatty acid ester, medium-chain fatty acid triglyceride of glycerin fatty acid ester, polyglycerin fatty acid ester, sorbitan fatty acid ester, propylene glycol fatty acid ester, special fatty acid ester, higher alcohol fatty acid ester, etc.

[0066] Other components may be contained in any layer in the sealant layer, or may not be contained. Also, the composition or content rate of other components may be changed in a plurality of heat-sealable resin layers.

[0067] Hereinafter, an example of the exterior material for a power storage device of the present disclosure will be described with reference to FIG. 1. FIG. 1 is a schematic cross-sectional view showing an example of the exterior material for a power storage device of the present disclosure. The exterior material 1 for a power storage device includes a base material layer 2, a barrier layer 4, and a sealant layer 3 in this order. The sealant layer 3 includes a first heat-sealable resin layer 7, a second heat-sealable resin layer 8, and a third heat-sealable resin layer 9 in order from the barrier layer 4 side. An outer adhesive layer 5 is provided between the base material layer 2 and the barrier layer 4, and an inner adhesive layer 6 is provided between the barrier layer 4 and the A layer 7.

[0068] <Method for manufacturing an exterior material for a power storage device> The method for manufacturing an exterior material for a power storage device is not particularly limited as long as the above-described exterior material for a power storage device can be obtained. The method for manufacturing an exterior material for a power storage device may include, for example, a step of applying the above-described adhesive of the present disclosure to the base material layer or the barrier layer, and a step of laminating the barrier layer or the base material layer on the adhesive. As an example of the method for manufacturing the exterior material 1 for a power storage device shown in FIG. 1, the method will be described below.

[0069] Prepare a laminate A in which a base material layer 2, an outer adhesive layer 5, and a barrier layer 4 are laminated in this order. The laminate A is produced by a dry lamination method in which an adhesive component for forming the outer adhesive layer 5 is applied to the base material layer 2 or the barrier layer 4 by a gravure coating method, a roll coating method, etc., dried, and then the barrier layer 4 or the base material layer 2 is laminated thereon. When the adhesive component is a curable resin, after laminating the barrier layer 4 or the base material layer 2 on the outer adhesive layer 5, the outer adhesive layer 5 is cured by heating or the like.

[0070] Next, a sealant layer 3 is provided on the barrier layer 4 of the laminate A. The sealant layer 3 may be a resin film previously formed and disposed on the barrier layer 4 (the first method), or a resin material for forming the sealant layer 3 may be applied on the barrier layer 4 by extrusion molding, coating, etc. to form the sealant layer 3 (the second method). In the first method, a resin film which is a multi-layer laminate such as a first heat-fusible resin layer 7, a second heat-fusible resin layer 8, and a third heat-fusible resin layer 9 can be produced by a co-extrusion method or the like.

[0071] In the case of the first method, the barrier layer 4 and the sealant layer 3 are adhered by an inner adhesive layer 6. In the case of the second method, the inner adhesive layer 6 may be omitted or the inner adhesive layer 6 may be provided.

[0072] When the inner adhesive layer 6 is provided between the barrier layer 4 and the sealant layer 3, the inner adhesive layer 6 and the sealant layer 3 can be laminated by an extrusion lamination method, a thermal lamination method, a sandwich lamination method, a dry lamination method, etc. Examples of the extrusion lamination method include a method (co-extrusion lamination method, tandem lamination method) of laminating by extruding an inner adhesive layer 6 and a sealant layer (a first heat-fusible resin layer 7, a second heat-fusible resin layer 8, and a third heat-fusible resin layer 9) on the barrier layer 4 of the laminate A. As the thermal lamination method, separately, a laminate B of the inner adhesive layer 6 and the sealant layer 3 is formed, and the laminate is performed such that the inner adhesive layer 6 of the laminate B faces the barrier layer 4 of the laminate A; a laminate C provided with the inner adhesive layer 6 is formed on the barrier layer 4 of the laminate A, and the inner adhesive layer 6 of the laminate C, the sealant layer 3 are laminated, etc. are exemplified. As the sandwich lamination method, a method of pouring the molten inner adhesive layer 6 between the barrier layer 4 of the laminate A and the sealant layer 3 previously formed in a film shape, etc. are exemplified. An adhesive resin such as an acid-modified polyolefin-based adhesive is poured between the barrier layer 4 of the laminate A and the sealant layer 3 previously formed in a film shape, sandwich laminated, and then heated with a thermal adhesive roll to bond the barrier layer 4 and the sealant layer 3 via the inner adhesive layer 6 (thermal adhesive resin) may be used. As the dry lamination method, a method of solution coating an adhesive component for forming the inner adhesive layer 6 on the barrier layer 4 of the laminate A, drying or baking, and laminating the sealant layer 3 previously formed in a film shape on the inner adhesive layer 6, etc. are exemplified.

[0073] <Outer case for power storage device> The outer case for power storage device of the present disclosure is a molded body of the above-described outer packaging material for power storage device. The outer packaging material for power storage device may be molded by deep drawing molding, protruding molding, etc. As the shape of the outer case for power storage device, for example, the outer cases 10 of FIGS. 2 and 3 described later are exemplified.

[0074] <Power storage device> The power storage device of the present disclosure includes a power storage device main body, and an outer member that houses the power storage device main body and includes the above-described outer packaging material for power storage device of the present disclosure. The outer member may be configured to include the outer case for power storage device of the present disclosure.

[0075] An example of a power storage device 100 configured using the exterior material 1 for a power storage device of the present disclosure is shown in FIGS. 2 and 3. FIG. 2 is a schematic cross-sectional view showing an example of the power storage device. FIG. 3 is a schematic perspective view showing a state in which the components constituting the power storage device of FIG. 2 are separated. The power storage device 100 is a lithium-ion secondary battery.

[0076] In FIGS. 2 and 3, an exterior member 15 is constituted by an exterior case 10 which is a molded body of the exterior material 1 and a planar exterior material 1. A power storage device main body portion 110 is housed in the housing recess of the exterior case 10. Then, the planar exterior material 1 is arranged with the sealant layer 3 side facing inward (downward in FIGS. 2 and 3), and the peripheral edge of the sealant layer 3 of the planar exterior material 1 and the sealant layer 3 of the flange portion (sealing peripheral edge portion) 37 of the exterior case 10 are sealed and joined by heat fusion (heat seal).

[0077] In FIG. 2, reference numeral 39 is a heat seal portion where the peripheral edge of the exterior material 1 and the flange portion (sealing peripheral edge portion) 37 of the exterior case 10 are joined (welded). In the power storage device 100, the tip of the tab lead connected to the power storage device main body portion 110 is led out to the outside of the exterior member 15, but the illustration is omitted.

[0078] The power storage device main body portion 110 is not particularly limited, and examples include a battery main body portion, a capacitor main body portion, a condenser main body portion, and the like.

[0079] From the viewpoint of ensuring sealing, the width of the heat seal portion 39 is preferably set to 0.5 mm or more, and more preferably set to 3 mm to 15 mm.

[0080] The form of the exterior member 15 is not limited to FIGS. 2 and 3, and the peripheries may be heat fused (heat sealed) with a pair of planar exterior materials 1, or the peripheries may be heat fused (heat sealed) with a pair of exterior cases 10.

Example

[0081] Next, examples of the present disclosure will be described, but the present disclosure is not particularly limited to these examples.

[0082] [Example 1] (Preparation of Adhesive) Zinc cyanurate was added to a two-component curable urethane-based adhesive component containing a polyester polyol compound and an aromatic polyisocyanate compound to prepare an adhesive for manufacturing an exterior material for a power storage device. At this time, 1% by mass of zinc cyanurate was added based on the total amount of the urethane-based adhesive component.

[0083] (Preparation of Laminate A) A chemical conversion treatment liquid composed of phosphoric acid, polyacrylic acid (acrylic resin), chromium (III) salt compound, water, and alcohol was applied to both sides of an aluminum foil with a thickness of 40 μm, and then dried at 180 °C to form a chemical conversion film. The chromium adhesion amount of this chemical conversion film was 10 mg / m per side. 2 It was.

[0084] Next, an adhesive for manufacturing an exterior material for a power storage device was applied to one surface of the chemically converted aluminum foil, and a biaxially stretched 6-nylon film with a thickness of 25 μm was dry laminated (bonded) through the adhesive. Corona treatment was performed on both surfaces of the biaxially stretched 6-nylon film. Thus, a laminate A in which a base material layer, an adhesive layer, and a barrier layer were laminated in this order was manufactured.

[0085] (Measurement of Shear Adhesion Strength) Two of the above-mentioned laminates A were prepared. The adhesive prepared as described above was applied to the central portion in the width direction of the surface on the aluminum foil side of the laminate A so as to have a width of 15 mm. Another laminate A was laminated on the 15-mm-wide adhesive so that the 15-mm-wide adhesive faced the nylon-side surface of another laminate A, and the laminate was aged (heated) at 50 °C for 5 days. Thus, a laminate D composed of laminate A, a 15-mm-wide adhesive, and laminate A was manufactured. The laminate D was cut in the thickness direction along the width direction to prepare a sample for measuring the shear adhesion strength composed of the cut laminate A, a 15 mm × 15 mm adhesive, and the cut laminate A. Regarding the sample for measuring the shear adhesion strength, the shear adhesion strength of the adhesive of 15 mm × 15 mm was measured by pulling a pair of cut laminates A upward and downward. The results are shown in Table 1.

[0086] (Fabrication of the exterior material for the power storage device) A chemical conversion treatment solution composed of phosphoric acid, polyacrylic acid (acrylic resin), chromium(III) salt compound, water, and alcohol was applied to both sides of an aluminum foil with a thickness of 35 μm, and then dried at 180 °C to form a chemical conversion film. The chromium adhesion amount of this chemical conversion film was 10 mg / m per side. 2 It was.

[0087] Next, an adhesive for fabricating the exterior material for the power storage device was applied to one surface of the chemically treated aluminum foil, and a biaxially stretched 6-nylon film with a thickness of 15 μm was dry laminated (bonded) through the adhesive. The bonding surface of the biaxially stretched 6-nylon film was subjected to corona treatment. Next, a first resin layer with a thickness of 4.5 μm made of an ethylene-propylene random copolymer, a second resin layer with a thickness of 21 μm made of an ethylene-propylene block copolymer resin, and a first resin layer with a thickness of 4.5 μm made of an ethylene-propylene random copolymer were coextruded in this order using a T-die so that these three layers were laminated to obtain a sealant film with a thickness of 30 μm (first resin layer / second resin layer / first resin layer). Then, one surface of the first resin layer of the sealant film (inner layer) was overlapped with the other surface of the aluminum foil after dry lamination through a two-component curable maleic acid-modified polypropylene adhesive (the curing agent is a polyfunctional isocyanate), and dry laminated by sandwiching it between a rubber nip roll and a laminating roll heated to 100 °C and pressing it. Thereafter, an exterior material for the power storage device with a thickness of 86 μm was fabricated by aging (heating) at 50 °C for 5 days.

[0088] (Measurement of the tensile elongation) The above-mentioned exterior material for the power storage device was cut into 15 mm × 150 mm to prepare samples for tensile elongation. A tensile test was conducted under the conditions of a speed of 100 mm / min and a gap of 100 mm, and the elongation at break was measured. The results are shown in Table 1.

[0089] (Forming evaluation) The prepared exterior material for the power storage device was cut into 100 mm × 125 mm to be used as a forming material. Then, a punch (punch shape: 33 mm × 54 mm, corner R: 2 mm, punch shoulder R: 1.3 mm) and a die (die shape: die shoulder R: 1 mm) were used, and deep drawing forming was performed using a press machine (model number: TP-25C-XZ) manufactured by Amada Co., Ltd. The above deep drawing forming was carried out in a manner where the top surface of the punch was brought into contact with the sealant layer of the forming material to protrude the base material layer outward, and the forming depth D was changed in 0.5 mm increments. Then, the corner part of the formed product was illuminated, and the presence or absence of transmitted light due to pinholes, cracks, etc. was visually observed, and the maximum forming depth (mm) at which good forming without the occurrence of pinholes and cracks could be achieved was examined. In Examples 1 to 3, 7 to 9 and Comparative Examples 3, 4 using urethane-based adhesives, based on the maximum forming depth (mm) of Comparative Example 1, and in Examples 4 to 6 and Comparative Example 5 using ester-based adhesives, based on the maximum forming depth (mm) of Comparative Example 2, the formability was evaluated based on the following evaluation criteria. It was determined that evaluations A to C indicated good formability, and evaluation D indicated poor formability. The results are shown in Table 1. -Evaluation criteria- A: The maximum forming depth is improved by 1.5 mm or more compared with Comparative Example 1 or 2 B: The maximum forming depth is improved by 1.0 mm or more and less than 1.5 mm compared with Comparative Example 1 or 2 C: The maximum forming depth is improved by 0.5 mm or more and less than 1.0 mm compared with Comparative Example 1 or 2 D: The maximum forming depth is improved by less than 0.5 mm compared with Comparative Example 1 or 2, or the maximum forming depth is the same as or less than that of Comparative Example 1 or 2

[0090] [Examples 2 and 3] In Example 1, an adhesive for manufacturing an exterior material for an electric storage device was prepared in the same manner as in Example 1, except that zinc cyanurate was added in an amount of 2% by mass or 3% by mass based on the total amount of the urethane-based adhesive components. Then, laminate A and the exterior material for an electric storage device were produced in the same manner as in Example 1, and the above-described physical property measurements and molding evaluations were performed.

[0091] [Example 4] (Preparation of Adhesive) Zinc cyanurate was added to a two-component curable ester-based adhesive component containing a polyester polyol compound and an aliphatic polyisocyanate compound to prepare an adhesive for manufacturing an exterior material for an electric storage device. At this time, zinc cyanurate was added in an amount of 1% by mass based on the total amount of the ester-based adhesive component. Then, laminate A and the exterior material for an electric storage device were produced in the same manner as in Example 1, and the above-described physical property measurements and molding evaluations were performed.

[0092] [Examples 5 and 6] In Example 4, an adhesive for manufacturing an exterior material for an electric storage device was prepared in the same manner as in Example 4, except that zinc cyanurate was added in an amount of 2% by mass or 3% by mass based on the total amount of the ester-based adhesive component. Then, laminate A and the exterior material for an electric storage device were produced in the same manner as in Example 4, and the above-described physical property measurements and molding evaluations were performed.

[0093] [Example 7] Zinc cyanurate and a pigment (carbon black) were added to a two-component curable urethane-based adhesive component containing a polyester polyol compound and an aromatic polyisocyanate compound to prepare an adhesive for manufacturing an exterior material for an electric storage device. At this time, zinc cyanurate was added in an amount of 1% by mass based on the total amount of the urethane-based adhesive component, and the pigment was added in an amount of 4.3% by mass based on the total amount of the resin solid content contained in the urethane-based adhesive component. Then, laminate A and the exterior material for an electric storage device were produced in the same manner as in Example 1, and the above-described physical property measurements and molding evaluations were performed.

[0094] [Examples 8 and 9] In Example 7, an adhesive for producing an exterior material for a power storage device was prepared in the same manner as in Example 7, except that zinc cyanurate was added in an amount of 2% by mass or 3% by mass based on the total amount of the urethane-based adhesive components. Then, a laminate A and an exterior material for a power storage device were produced in the same manner as in Example 7, and the above-described physical property measurements and molding evaluations were performed.

[0095] [Comparative Example 1] A two-component curable urethane-based adhesive component containing a polyester polyol compound and an aromatic polyisocyanate compound was used as the adhesive for producing the exterior material for the power storage device in Comparative Example 1. Then, a laminate A and an exterior material for a power storage device were produced in the same manner as in Example 1, and the above-described physical property measurements and molding evaluations were performed.

[0096] [Comparative Example 2] A two-component curable ester-based adhesive component containing a polyester polyol compound and an aliphatic polyisocyanate compound was used as the adhesive for producing the exterior material for the power storage device in Comparative Example 2. Then, a laminate A and an exterior material for a power storage device were produced in the same manner as in Example 1, and the above-described physical property measurements and molding evaluations were performed.

[0097] [Comparative Example 3] A pigment (carbon black) was added to a two-component curable urethane-based adhesive component containing a polyester polyol compound and an aromatic polyisocyanate compound to prepare an adhesive for producing an exterior material for a power storage device. At this time, the pigment was added in an amount of 4.3% by mass based on the total amount of the resin solids contained in the urethane-based adhesive component. Then, a laminate A and an exterior material for a power storage device were produced in the same manner as in Example 1, and the above-described physical property measurements and molding evaluations were performed.

[0098] [Comparative Example 4] In Example 1, an adhesive for producing an exterior material for a power storage device was prepared in the same manner as in Example 1, except that zinc cyanurate was added in an amount of 5% by mass based on the total amount of the urethane-based adhesive components. Then, a laminate A and an exterior material for a power storage device were produced in the same manner as in Example 1, and the above-described physical property measurements and molding evaluations were performed.

[0099] [Comparative Example 5] In Example 4, an adhesive for producing an exterior material for a power storage device was prepared in the same manner as in Example 1, except that 5% by mass of zinc cyanurate was added to the total amount of the ester-based adhesive component. Then, a laminate A and an exterior material for a power storage device were produced in the same manner as in Example 1, and the above-described physical property measurement and molding evaluation were performed.

[0100]

Table 1

[0101] As shown in Table 1, when the adhesives of Examples 1 to 9 were used, the molding evaluation was good as compared with the case where the adhesives of Comparative Examples 1 to 5 were used. In Examples 1 to 3, the shear adhesion strength was improved by 20% or more by adding 1 to 3% by mass of an additive to Comparative Example 1. In Examples 4 to 6, the shear adhesion strength was improved by 20% or more by adding 1 to 3% by mass of an additive to Comparative Example 2. In Examples 7 to 9, the shear adhesion strength was improved by 20% or more by adding 1 to 3% by mass of an additive to Comparative Example 3. In any of the examples, the molding evaluation was improved.

Claims

1. An adhesive for forming an adhesive layer between a base material layer and a barrier layer in the production of an exterior material for a power storage device, which contains an adhesive component and has a shear adhesive strength of 0.7 MPa or more.

2. An adhesive containing an adhesive component and an additive, wherein the rate of increase in shear adhesive strength with respect to a comparative adhesive having the same composition except for not containing the additive is 20% or more, and is used for forming an adhesive layer between a base material layer and a barrier layer in the production of an exterior material for a power storage device.

3. The adhesive according to claim 1, wherein the adhesive component contains at least one selected from the group consisting of polyester and polyurethane.

4. The adhesive according to claim 3, further containing a metal salt containing an amino group and a carbonyl group.

5. The adhesive according to claim 2, wherein the additive contains a metal salt containing an amino group and a carbonyl group.

6. The adhesive according to claim 4, wherein the content of the metal salt is 0.5% by mass to 4% by mass based on the solid content of the adhesive.

7. The adhesive according to claim 5, wherein the content of the metal salt is 0.5% by mass to 4% by mass based on the solid content of the adhesive.

8. An exterior material for a power storage device, in which a base material layer, an adhesive layer formed by the adhesive according to any one of claims 1 to 7, a barrier layer, and a sealant layer are laminated in this order.

9. A step of applying the adhesive according to any one of claims 1 to 7 to the base material layer or the barrier layer, and a step of laminating the barrier layer or the base material layer on the adhesive, A manufacturing method for an exterior material for a power storage device, comprising:

10. An exterior case for a power storage device, which is a molded body of the exterior material for a power storage device according to claim 8.

11. A power storage device, comprising: a power storage device main body, and an exterior member that houses the power storage device main body and includes the exterior material for a power storage device according to claim 10.

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