Laminated body for outer packaging material of power storage device

Abstract

To provide a laminated body for a power storage device outer packaging material, capable of obtaining sufficient formability.SOLUTION: A laminated body 1 for a power storage device outer packaging material of the present invention includes: a barrier layer 3 made of metal; a base material layer 2 made of a heat-resistant resin laminated on an outer side surface of the barrier layer 3; and a sealant layer 4 made of a heat sealable resin laminated on an inner side surface of the barrier layer 3. The base material layer 2 includes a polyester film layer 21 as an outer layer and a polyamide film layer 22 as an inner layer. The polyester film layer 21 is 500 MPa to 600 MPa in a sum of tensile breaking strength in an MD and tensile breaking strength in a TD, 0.8 to 1.1 in a ratio of the tensile breaking strength in the TD to the tensile breaking strength in the MD, and 110% to 200% in tensile breaking elongation in the MD and tensile breaking elongation in the TD. The MD denotes a machine flow direction, and the TD denotes a direction perpendicular to the MD.SELECTED DRAWING: Figure 1

Description

Technical Field

[0001] The present invention relates to a laminate for an outer package of a power storage device, which is composed of a laminate material in which a resin layer is laminated on a metal layer.

Background Art

[0002] Conventionally, battery packages for housing batteries have mostly been made of metal processed into a cylindrical type or a rectangular type. In recent years, batteries, as one of the diversifying energy supply sources and energy storages, have come to be used in various places, and weight reduction and space saving have also been required.

[0003] As one countermeasure, a metal-resin laminate sheet (hereinafter referred to as a laminate sheet) in which resin films are laminated on both sides of a metal foil has come to be used as a battery package. By using it as a sheet or performing deep drawing molding according to the shape of the storage space, it has become possible to provide a battery with the maximum capacity in a limited space.

[0004] Since a battery using this laminate sheet is excellent in corrosion resistance and sealing performance, for example, its application to the packaging of large batteries for driving automobiles such as electric vehicles (EVs) and plug-in hybrid electric vehicles (PHEVs) has been promoted. As a configuration example of a packaging material for a large battery that can withstand use in a harsh environment, a configuration in which a base material layer arranged outside a metal foil is multi-layered has been proposed. (See Patent Documents 1 to 3 below) In the present invention, the outside means the side opposite to the storage space in the battery package, and the inside means the side of the storage space in the battery package.

[0005] In Patent Document 1, a battery package having puncture strength, tensile strength, bendability, heat resistance, and chemical resistance is proposed by forming the base material layer into a two-layer structure of a PET film / ONY film.

[0006] In Patent Document 2 as well, a battery packaging material having heat resistance, water resistance, and chemical resistance (prevention of whitening of the ONY film by the electrolyte) has been proposed by forming the base material layer into a two-layer structure of a PET film / ONY film.

[0007] Further, in Patent Document 3, a packaging material for in-vehicle batteries having vibration resistance and formability considering vibrations during vehicle travel has been proposed by forming the base material layer into a two-layer structure of a PET film / ONY film and further defining the range of the tensile breaking strength and tensile breaking elongation of the PET film.

Prior Art Documents

Patent Documents

[0008]

Patent Document 1

Patent Document 2

Patent Document 3

Summary of the Invention

Problems to be Solved by the Invention

[0009] However, in Patent Documents 1 and 2, specific physical properties of the PET film and ONY film of the base material layer are not described. Since the base material layer is made into a multi-layer structure (two-layer structure), there is a problem that when stricter formability (deeper forming height) is required for the purpose of improving battery capacity, it may not be satisfactory.

[0010] Further, in Patent Document 3, specific descriptions of the physical properties of the ONY film are not provided, and there is a problem that sufficient formability cannot be obtained when the formed shape is sharp and the forming height is high even in a four-layer packaging material (PET / ONY / AL / sealant).

[0011] The present invention has been made in view of such a technical background, and in a four-layer battery packaging material assuming a packaging material for in-vehicle batteries, it is an object to provide a laminate for an outer packaging material of a power storage device that can obtain sufficient formability even when the formed shape is sharp and the formed height is high.

Means for Solving the Problems

[0012] In order to achieve the above object, the present invention provides the following means.

[0013] [1] A barrier layer made of metal, A base material layer made of a heat-resistant resin laminated on the outer surface of the barrier layer, A laminate for an outer packaging material of a power storage device, comprising a sealant layer made of a heat-sealable resin laminated on the inner surface of the barrier layer, The base material layer is composed of a polyester film layer as an outer layer and a polyamide film layer as an inner layer, The polyester film layer is characterized in that the sum of the tensile breaking strength in the MD direction and the tensile breaking strength in the TD direction is 500 MPa to 600 MPa, the ratio of the tensile breaking strength in the TD direction to the tensile breaking strength in the MD direction is 0.8 to 1.1, and the tensile breaking elongation in the MD direction and the tensile breaking elongation in the TD direction are 110% to 200%. A laminate for an outer packaging material of a power storage device. However, MD: Machine flow direction, TD: Direction perpendicular to MD

[0014] [2] The laminate for an outer packaging material of a power storage device according to item 1 above, wherein the polyamide film layer has a hot water shrinkage rate in the MD direction and a hot water shrinkage rate in the TD direction of 2.5% to 6%.

[0015] [3] The laminate for an outer packaging material of a power storage device according to item 1 or 2 above, wherein the sum of the tensile breaking strength in the MD direction and the tensile breaking strength in the TD direction of the polyamide film layer is 550 MPa to 700 MPa, and the tensile breaking elongation in the MD direction and the tensile breaking elongation in the TD direction are 90% to 200%.

[0016] [4] An adhesive layer between the base materials is laminated between the polyester film layer and the polyamide film layer, The adhesive layer between the base materials is a laminate for an outer package of an electric storage device according to the preceding items 1 to 3, having a Young's modulus of 70 MPa to 400 MPa, a breaking strength of 20 MPa to 70 MPa, and an elongation at break of 50% to 400%.

[0017] [5] The adhesive layer between the base materials is composed of a cured product of an adhesive containing, as a main component, one or more resins selected from polyurethane resins, polyester polyurethane resins, polyether polyurethane resins, polyether resins, and polyester resins, and a polyfunctional isocyanate as a curing agent, and is the laminate for an outer package of an electric storage device according to the preceding item 4. [Advantages of the Invention]

[0018] [1] According to the invention of [1], the base material layer is composed of a polyester film layer as an outer layer and a polyamide film layer as an inner layer. By setting the sum of the tensile breaking strength in the MD direction and the tensile breaking strength in the TD direction of the polyester film layer to be 500 MPa to 600 MPa, the ratio of the tensile breaking strength in the TD direction to the tensile breaking strength in the MD direction to be 0.8 to 1.1, and the tensile elongation at break in the MD direction and the tensile elongation at break in the TD direction to be 110% to 200%, the polyester film layer becomes difficult to break, so that sufficient formability can be obtained even when the molding shape is sharp and the molding height is high (deeper drawing molding can be performed).

[0019] In addition, by using a polyester film layer for the outer layer of the base material layer, chemical resistance and impact resistance can also be enhanced.

[0020] [2] According to the invention of [2], by setting the hot water shrinkage rate in the MD direction and the hot water shrinkage rate in the TD direction to be 2.5% to 6%, the piercing strength of the polyamide film layer is increased, so that it can be made more difficult to break.

[0021] In a base material layer composed of a high-strength polyester film layer and a high-strength and tear-resistant polyamide film layer, by setting the hot water shrinkage rate in the MD direction and the hot water shrinkage rate in the TD direction of the polyamide film layer to 2.5% to 6%, it is possible to suppress the occurrence of molding cracks in the molding portion near the shoulder R of the punch that undergoes the most severe molding process for molding conditions and mold shapes that require small and deep corner R for the purpose of increasing the energy density.

[0022] According to the invention of [3], since the sum of the tensile breaking strength in the MD direction and the tensile breaking strength in the TD direction of the polyamide film layer is 550 MPa to 700 MPa, and the tensile breaking elongation in the MD direction and the tensile breaking elongation in the TD direction are 90% to 200%, the polyamide film layer is less likely to be torn during molding, so the moldability can be further improved.

[0023] According to the invention of [4], an adhesive layer between base materials is laminated between the polyester film layer and the polyamide film layer. The adhesive layer between base materials has a Young's modulus of 70 MPa to 400 MPa, a breaking strength of 20 MPa to 70 MPa, and a breaking elongation of 50% to 400%. During the molding process, it follows the deformation behavior of the polyamide film layer, and peeling between the polyamide film layer and the adhesive layer between base materials is less likely to occur, and the characteristics (especially elongation and tear resistance) of the polyamide film layer can be transmitted (added) to the barrier layer.

[0024] According to the invention of [5], the adhesive layer between base materials is composed of a cured product of an adhesive that uses one or more resins selected from polyurethane-based resins, polyester polyurethane-based resins, polyether polyurethane-based resins, polyether-based resins, and polyester-based resins as the main agent and polyfunctional isocyanate as the curing agent, so that the occurrence of delamination and the like can be further suppressed.

Brief Description of the Drawings

[0025]

Figure 1

Figure 2

Figure 3

DETAILED DESCRIPTION OF THE INVENTION

[0026] The laminate for the outer packaging material of the power storage device of the present invention constitutes an outer packaging material for housing the power storage device.

[0027] As shown in FIG. 1, the laminate 1 for the outer packaging material of the power storage device of the present embodiment has a structure in which a sealant layer 4 is laminated on the inner surface of a barrier layer 3 via a first adhesive layer 7, and a base material layer 2 is laminated on the outer surface of the barrier layer 3 via a second adhesive layer 6.

[0028] The base material layer of the present invention is made of a heat-resistant resin and is laminated on the outer surface of the barrier layer described later. The heat-resistant resin forming the base material layer is a resin having a melting point 10 °C or higher, more preferably 20 °C or higher, than the heat-sealable resin forming the sealant layer described later.

[0029] The base material layer 2 of the present embodiment has a two-layer structure and is composed of a polyester film layer 21 and a polyamide film layer 22.

[0030] The polyester film layer of the present invention constitutes the outer layer of the base material layer.

[0031] The polyester film layer 21 of the present embodiment has the following characteristics in terms of the tensile breaking strength in the MD and TD directions and the tensile breaking elongation in the MD and TD directions. Here, MD means the "machine flow direction", and TD means the "direction orthogonal to the MD (machine flow direction)".

[0032] In the polyester film layer 21 of the present embodiment, the sum of the tensile breaking strength in the MD direction and the tensile breaking strength in the TD direction is 500 MPa to 600 MPa, and preferably 520 MPa to 580 MPa.

[0033] If the sum of the tensile breaking strength in the MD direction and the tensile breaking strength in the TD direction is less than 500 MPa, breakage will occur at locations (near the shoulder R of the punch) where severe forming processes are applied. On the other hand, if it exceeds 600 MPa, the tensile breaking strength of the polyester film layer becomes too high and it cannot be formed into a predetermined shape.

[0034] Also, the ratio of the tensile breaking strength in the TD direction to the tensile breaking strength in the MD direction is 0.8 to 1.1, and preferably 0.85 to 0.95.

[0035] If the ratio of the tensile breaking strength in the TD direction to the tensile breaking strength in the MD direction is less than 0.8, breakage will occur at locations where severe forming processes are applied because the tensile breaking strength in the TD direction is weak. On the other hand, if it exceeds 1.1, it is necessary to increase the stretching in the TD direction during film formation of the polyester film layer, which makes film formation difficult and is also disadvantageous in terms of cost.

[0036] Furthermore, in the polyester film layer 21 of the present embodiment, both the tensile breaking elongation in the MD direction and the tensile breaking elongation in the TD direction are 110% to 200%.

[0037] If the tensile breaking elongation in the MD direction and the tensile breaking elongation in the TD direction are less than 110%, breakage will occur at locations (near the shoulder R of the punch) where severe forming processes are applied. On the other hand, even if it exceeds 200%, there is no significant difference in the effect on the forming process.

[0038] Also, as the polyester film layer 21 of the present embodiment, a polyethylene terephthalate (PET) film, a polybutylene terephthalate (PBT) film, a polyethylene naphthalate (PEN) film, etc. can be used, and preferably these stretched films are used.

[0039] Also, the thickness of the polyester film layer 21 of the present embodiment is preferably 6 μm to 50 μm, and more preferably 12 μm to 25 μm.

[0040] In order to improve the adhesion to the base material adhesive layer 5 described later, it is preferable to laminate an easy-adhesion layer on at least one side of the polyester film layer 21 or perform corona treatment. By laminating the easy-adhesion layer, excellent adhesion and adhesive strength can be improved. The method of laminating the easy-adhesion layer is not particularly limited, but it is preferably laminated by in-line coating. This is because the easy-adhesion layer can be uniformly formed on the surface of the polyester film layer 21.

[0041] As the easy-adhesion layer, for example, acrylic resins, urethane resins, polyester resins, olefin resins, fluorine resins, vinyl resins, chlorine resins, styrene resins, various graft resins, epoxy resins, silicone resins, etc. can be used, and mixtures of these resins may also be used. Among them, from the viewpoint of adhesion, it is preferable to use an acrylic resin or a polyester resin.

[0042] The polyamide film layer of the present invention constitutes the inner layer of the base material layer.

[0043] In the polyamide film layer 22 of the present embodiment, both the hot water shrinkage rate in the MD direction and the hot water shrinkage rate in the TD direction at 100 °C for 30 minutes are 2.5% to 6%, and more preferably 3% to 5%.

[0044] If the hot water shrinkage rate in the MD direction and the hot water shrinkage rate in the TD direction are less than 2.5%, breakage will occur at locations (near the shoulder R of the punch) where severe forming processes are applied. On the other hand, if it exceeds 6%, springback (deformation) of the flange portion is likely to occur after forming or heat sealing.

[0045] By setting the hot water shrinkage rate in the MD direction and the hot water shrinkage rate in the TD direction of the polyamide film layer 22 to be 2.5% to 6% in this way, the piercing strength of the polyamide film layer 22 is increased, so it can be made more difficult to tear.

[0046] Further, in the base material layer 2 composed of the high-strength polyester film layer 21 and the high-strength and tear-resistant polyamide film layer 22, by setting the hot water shrinkage rate in the MD direction and the hot water shrinkage rate in the TD direction of the polyamide film layer 22 to be 2.5% to 6%, for the molding conditions and mold shapes that require a small and deep corner R for the purpose of increasing the energy density, the occurrence of molding cracks in the molding part near the shoulder R of the punch that undergoes the most severe molding process can be suppressed.

[0047] Also, in the polyamide film layer 22 of the present embodiment, the sum of the tensile breaking strength in the MD direction and the tensile breaking strength in the TD direction is 550 MPa to 700 MPa, and preferably 550 MPa to 650 MPa.

[0048] If the sum of the tensile breaking strength in the MD direction and the tensile breaking strength in the TD direction is less than 550 MPa, breakage will occur at the location where severe molding process is applied (near the shoulder R of the punch). On the other hand, if it exceeds 700 MPa, the tensile breaking strength of the polyamide film layer becomes too high and it cannot be molded into a predetermined shape.

[0049] Also, both the tensile breaking elongation in the MD direction and the tensile breaking elongation in the TD direction are 90% to 200%.

[0050] If the tensile breaking elongation in the MD direction and the tensile breaking elongation in the TD direction are less than 90%, breakage will occur at the location where severe molding process is applied (near the shoulder R of the punch). On the other hand, even if it exceeds 200%, there is no significant difference in the effect on the molding process.

[0051] In this way, since the sum of the MD tensile breaking strength and the TD tensile breaking strength of the polyamide film layer 22 is 550 MPa to 700 MPa, and the MD tensile breaking elongation and the TD tensile breaking elongation are 90% to 200%, the polyamide film layer 22 is less likely to be torn during molding, so that the moldability can be further improved.

[0052] As the polyamide film layer 22 of this embodiment, a 6-nylon film, a 6,6-nylon film, etc. can be used, and among them, it is preferable to use these stretched films.

[0053] Also, the thickness of the polyamide film layer 22 of this embodiment is preferably 10 μm to 50 μm, and more preferably 15 μm to 25 μm among them.

[0054] It is preferable to perform corona treatment or laminate an easy-adhesion layer on the polyamide film layer 22 of this embodiment. In particular, by providing the easy-adhesion layer on the barrier layer 3 side, excellent adhesion and adhesive strength with the barrier layer 3 can be improved. The method for forming the easy-adhesion layer is not particularly limited. For example, an aqueous emulsion (aqueous system emulsion) of one or more resins selected from the group consisting of epoxy resin, urethane resin, acrylate resin, methacrylate resin, and polyethyleneimine resin is applied to the surface of the polyamide film layer 22 and dried to form the easy-adhesion layer. The coating method is not particularly limited, and examples thereof include spray coating method, gravure roll coating method, reverse roll coating method, lip coating method, etc. In addition, it is more preferable to perform corona treatment or the like on the film surface in advance to improve wettability before laminating the easy-adhesion layer.

[0055] Among them, it is particularly preferable that the easy-adhesion layer has a configuration containing urethane resin and epoxy resin, or a configuration containing (meth)acrylate resin and epoxy resin. In this case, the occurrence of delamination between the polyamide film layer 22 and the barrier layer 3 can be more sufficiently suppressed.

[0056] In this embodiment, as shown in FIG. 1, an inter-substrate adhesive layer 5 is laminated between a polyester film layer 21 and a polyamide film layer 22.

[0057] The inter-substrate adhesive layer of the present invention is a layer responsible for joining the polyester film layer and the polyamide film layer.

[0058] In the inter-substrate adhesive layer 5 of this embodiment, the Young's modulus is 70 MPa to 400 MPa, and preferably 100 MPa to 300 MPa among them.

[0059] When the Young's modulus is less than 70 MPa, the adhesive coating film breaks during the forming process, and this broken part becomes an adhesion defect, resulting in forming breakage. On the other hand, when it exceeds 400 MPa, the adhesive coating film becomes too hard and the adhesive force decreases. Therefore, peeling from the stretched film (polyamide film layer) during the forming process is likely to occur.

[0060] Also, the breaking strength of the inter-substrate adhesive layer 5 is 20 MPa to 70 MPa, and preferably 30 to 50 MPa among them.

[0061] When the breaking strength is less than 20 MPa, the adhesive coating film breaks during the forming process, and this broken part becomes an adhesion defect, resulting in forming breakage. On the other hand, when it exceeds 70 MPa, the adhesive coating film becomes too hard and the adhesive force decreases. Therefore, peeling from the stretched film (polyamide film layer) during the forming process is likely to occur.

[0062] Furthermore, the elongation at break of the inter-substrate adhesive layer 5 is 50% to 400%, and preferably 100% to 300% among them.

[0063] When the elongation at break is less than 50%, the adhesive coating film breaks during the forming process, and this broken part becomes an adhesion defect, resulting in forming breakage. On the other hand, even when it exceeds 400%, there is no significant difference in the effect on the forming process.

[0064] The mechanical properties of the above Young's modulus, breaking strength, and elongation at break are values measured in accordance with JIS K7161-2(2014) for the bulk (cured product) test piece of the adhesive (the test piece of the two-component curing type adhesive is a 0.5 mm thick test piece prepared in accordance with JIS K6878-1(2011)).

[0065] Thus, in this embodiment, the inter-substrate adhesive layer 5 is laminated between the polyester film layer 21 and the polyamide film layer 22. The inter-substrate adhesive layer 5 has a Young's modulus of 70 MPa to 400 MPa, a breaking strength of 20 MPa to 70 MPa, and an elongation at break of 50% to 400%. During the molding process, it follows the deformation behavior of the polyamide film layer 22, making it difficult for peeling to occur between the polyamide film layer 22 and the inter-substrate adhesive layer 5, and the characteristics of the polyamide film layer 22 (especially elongation and tear resistance) can be transmitted (added) to the barrier layer 3.

[0066] Also, as the inter-substrate adhesive layer 5 of this embodiment, it is preferable to use a cured product of an adhesive having one or more resins selected from polyurethane resins, polyester polyurethane resins, polyether polyurethane resins, polyether resins, and polyester resins as the main component and polyfunctional isocyanate as the curing agent. An epoxy adhesive, an acrylic adhesive, a polyester amide adhesive, or a polyamide adhesive may also be used.

[0067] Also, the thickness of the inter-substrate adhesive layer 5 is preferably 1 μm to 5 μm.

[0068] Examples of the polyfunctional isocyanate include aromatic polyfunctional isocyanate, aliphatic polyfunctional isocyanate having an aromatic ring, and aliphatic polyfunctional isocyanate.

[0069] The aromatic polyfunctional isocyanate is not particularly limited. For example, tolylene diisocyanate (TDI), diphenylmethane diisocyanate (MDI), triphenylmethane triisocyanate, etc. can be used.

[0070] Although the aliphatic polyfunctional isocyanate having an aromatic ring is not particularly limited, for example, xylylene diisocyanate (XDI), tetramethylxylylene diisocyanate (TMXDI), etc. can be used.

[0071] Although the aliphatic polyfunctional isocyanate is not particularly limited, for example, hexamethylene diisocyanate (HDI) can be used.

[0072] Thus, by forming the base material - to - base material adhesive layer 5 from a cured product of an adhesive having one or more resins selected from polyurethane - based resins, polyester - polyurethane - based resins, polyether - polyurethane - based resins, polyether - based resins, and polyester - based resins as the main agent and a polyfunctional isocyanate as the curing agent, the occurrence of delamination and the like can be further suppressed.

[0073] The barrier layer of the present invention plays a role of imparting gas barrier properties to prevent the intrusion of oxygen and moisture into the laminate for the outer package of the power storage device.

[0074] As the barrier layer 3 of the present embodiment, aluminum foil, copper foil, stainless steel foil, nickel foil, titanium foil, etc. can be used. In particular, those of the 1000 series or 8000 series defined in JIS H4160 Aluminum foil are preferably used, and the thickness is preferably 20 μm to 100 μm.

[0075] Also, it is preferable to provide a chemical conversion treatment layer, such as a phosphoric acid chromate treatment or a zirconium - based chemical conversion treatment, on at least the inner surface of the barrier layer 3, that is, the surface on the side of the sealant layer described later. By performing such a chemical conversion treatment, corrosion of the surface of the barrier layer 3 by the content (such as the electrolyte of the battery) can be sufficiently prevented. For example, the barrier layer 3 is subjected to a chemical conversion treatment by performing the following treatment. That is, on the surface of the degreased metal foil, 1) An aqueous solution composed of a mixture of phosphoric acid, chromic acid, and a metal salt of fluoride 2) An aqueous solution composed of a mixture of phosphoric acid, chromic acid, a metal salt of fluoride, and a non - metal salt 3) An aqueous solution composed of a mixture of an acrylic resin or / and a phenolic resin, phosphoric acid, chromic acid, and a metal fluoride salt 4) An aqueous solution composed of a mixture of an acrylic resin or / and a phenolic resin, a phosphate or a phosphoric acid compound, a chromate or a chromic acid compound, and a metal fluoride salt A chemical conversion film is formed by applying the above solution and then drying it.

[0076] In this embodiment, a second adhesive layer 6 is laminated on the outer surface of the barrier layer 3.

[0077] The second adhesive layer 6 of this embodiment is a layer responsible for bonding the barrier layer 3 and the polyamide film layer 22.

[0078] As the second adhesive layer 6 of this embodiment, a urethane-based adhesive, an epoxy-based adhesive, or an acrylic-based adhesive can be used, and the thickness is preferably 1 μm to 5 μm.

[0079] In this embodiment, a sealant layer 4 is laminated on the inner surface of the barrier layer 3 via a first adhesive layer 7.

[0080] The sealant layer of the present invention is made of a heat-sealable resin and constitutes the innermost layer of the laminate for the outer packaging material of the power storage device.

[0081] As the sealant layer 4 of this embodiment, a polyolefin-based film (such as un-stretched polypropylene, linear low-density polyethylene, etc.) can be used, and the thickness is preferably 20 μm to 100 μm.

[0082] The first adhesive layer 7 of this embodiment is a layer responsible for bonding the barrier layer 3 and the sealant layer 4.

[0083] As the first adhesive layer 7 of this embodiment, an olefin-based adhesive or an epoxy-based adhesive can be used, and it is particularly preferable to use an acid-modified olefin-based adhesive.

[0084] As described above, in this embodiment, the base material layer 2 is composed of a polyester film layer 21 as an outer layer and a polyamide film layer 22 as an inner layer. The sum of the tensile break strength in the MD direction and the tensile break strength in the TD direction of the polyester film layer 21 is 500 MPa to 600 MPa, and the ratio of the tensile break strength in the TD direction to the tensile break strength in the MD direction is 0.8 to 1.1, and the tensile break elongation in the MD direction and the tensile break elongation in the TD direction are 110% to 200%. As a result, the polyester film layer 21 is less likely to be torn, so that sufficient formability can be obtained even when the molded shape is sharp and the molding height is high (deeper drawing molding can be performed).

[0085] In addition, since the polyester film layer 21 is used as the outer layer of the base material layer 2, the chemical resistance and impact resistance can also be enhanced.

[0086] FIG. 2 is a cross-sectional view showing an embodiment of the power storage device 7 formed using the laminate 1 for the power storage device outer package of this embodiment, and FIG. 3 is a perspective view showing a separated state before heat-sealing the outer package material 61 (flat), the power storage device main body 71, and the outer package case 62 (a molded body formed into a three-dimensional shape) constituting the power storage device 7 of FIG. 2.

[0087] The power storage device outer package material 61 composed of the laminate 1 for the power storage device outer package of this embodiment is used, for example, as an outer package material for a lithium ion secondary battery. This outer package material 61 may be used as it is without being molded, or may be molded, for example, by deep drawing molding, protruding molding, etc. and used as the outer package case 62.

[0088] In this embodiment, as shown in FIGS. 2 and 3, the outer package member 6 is constituted by the flat outer package material 61 and the outer package case 62 obtained by molding the outer package material 61.

[0089] Inside the housing recess of the outer casing 62, a power storage device main body 71 (such as an electrochemical element) having a substantially rectangular parallelepiped shape is housed. Above this power storage device main body 71, the outer packaging material 61 is arranged with the side of the sealing layer 4 facing inward (downward) without being formed. The peripheral edge of the sealing layer 4 in the outer packaging material 61 and the sealing layer 4 in the flange portion 63 of the outer casing 62 are joined and sealed by heat fusion at the heat seal portion 81, thereby constituting the power storage device 7.

[0090] Note that the inner surface of the housing recess in the outer casing 62 is the sealing layer 4, and the outer surface of the housing recess is the base material layer 2.

[0091] Also, the power storage device main body 71 is not particularly limited, and examples include a battery main body, a capacitor main body, a condenser main body, and the like.

[0092] In the above embodiment, the outer packaging member 6 is composed of a flat outer packaging material 61 and an outer casing 62 obtained by molding the outer packaging material 61. However, it is not particularly limited to such a combination. For example, the outer packaging member 6 may be composed of a pair of flat outer packaging materials 61, or may be composed of a pair of outer casings 62.

Example

[0093] Next, specific examples of the present invention will be described, but the present invention is not particularly limited to those of these examples.

[0094] <Example 1> A chemical conversion treatment liquid composed of polyacrylic acid, a trivalent chromium compound, water, and alcohol was applied to both sides of an aluminum foil (barrier layer 3) with a thickness of 40 μm and dried at 180 °C. The chemical conversion treatment was performed so that the chromium adhesion amount was 10 mg / m 2 Note that A8021-O material (JIS H4160 (2006)) was used as the aluminum foil.

[0095] Furthermore, a two-component curable urethane-based adhesive (second adhesive layer 6) was coated on one surface of this aluminum foil to a thickness of 4 μm by dry lamination, and a stretched nylon film (polyamide film layer 22) with a thickness of 15 μm was laminated.

[0096] Furthermore, a polyester urethane-based adhesive (adhesive layer 5 between substrates) was coated on the surface of this stretched nylon film to a thickness of 4 μm by dry lamination, and a stretched polyethylene terephthalate (PET) film (polyester film layer 21) with a thickness of 12 μm was laminated.

[0097] Furthermore, heat aging treatment was performed at 60°C for 7 days.

[0098] Next, an olefin-based adhesive (first adhesive layer 7) was coated on the other surface of the aluminum foil to a thickness of 3 μm, and a non-stretched polypropylene (CPP) film (sealant layer 4) with a thickness of 80 μm was laminated.

[0099] Furthermore, heat aging treatment was performed at 40°C for 10 days to produce the laminate 1 for the outer package of the power storage device of Example 1.

[0100] As the stretched polyethylene terephthalate (PET) film, one with a tensile breaking strength in the MD direction of 305 MPa, a tensile breaking strength in the TD direction of 272 MPa, that is, the sum of these being 577 MPa, a ratio of the tensile breaking strength in the TD direction to the tensile breaking strength in the MD direction of 0.89, a tensile breaking elongation in the MD direction of 138%, and a tensile breaking elongation in the TD direction of 160% was used.

[0101] As the stretched nylon film, one with a tensile breaking strength in the MD direction of 276 MPa, a tensile breaking strength in the TD direction of 310 MPa, that is, the sum of these being 586 MPa, a tensile breaking elongation in the MD direction of 120%, a tensile breaking elongation in the TD direction of 120%, a hot water shrinkage rate in the MD direction of 3.5%, and a hot water shrinkage rate in the TD direction of 3.8% was used.

[0102] As the polyester urethane-based adhesive, one with a Young's modulus of 150 MPa, a breaking strength of 40 MPa, and a breaking elongation of 200% was used.

[0103] <Example 2> As the stretched polyethylene terephthalate (PET) film, one having a tensile breaking strength in the MD direction of 280 MPa, a tensile breaking strength in the TD direction of 276 MPa, that is, the sum of these being 556 MPa, a ratio of the tensile breaking strength in the TD direction to the tensile breaking strength in the MD direction of 0.99, a tensile breaking elongation in the MD direction of 171%, and a tensile breaking elongation in the TD direction of 158% was used.

[0104] As the stretched nylon film, one having a tensile breaking strength in the MD direction of 280 MPa, a tensile breaking strength in the TD direction of 322 MPa, that is, the sum of these being 602 MPa, a tensile breaking elongation in the MD direction of 140%, a tensile breaking elongation in the TD direction of 120%, a hot water shrinkage rate in the MD direction of 3.6%, and a hot water shrinkage rate in the TD direction of 4.2% was used.

[0105] A laminate 1 for an outer package of an electric storage device was produced in the same manner as in Example 1 except that the above-mentioned materials were used.

[0106] <Example 3> As the stretched polyethylene terephthalate (PET) film, one having a tensile breaking strength in the MD direction of 271 MPa, a tensile breaking strength in the TD direction of 254 MPa, that is, the sum of these being 525 MPa, a ratio of the tensile breaking strength in the TD direction to the tensile breaking strength in the MD direction of 0.94, a tensile breaking elongation in the MD direction of 155%, and a tensile breaking elongation in the TD direction of 151% was used.

[0107] As the stretched nylon film, one having a tensile breaking strength in the MD direction of 276 MPa, a tensile breaking strength in the TD direction of 320 MPa, that is, the sum of these being 596 MPa, a tensile breaking elongation in the MD direction of 120%, a tensile breaking elongation in the TD direction of 110%, a hot water shrinkage rate in the MD direction of 3.4%, and a hot water shrinkage rate in the TD direction of 4.2% was used.

[0108] A laminate 1 for an outer package of an electric storage device was produced in the same manner as in Example 1 except that the above-mentioned materials were used.

[0109] <Example 4> As the stretched polyethylene terephthalate (PET) film, one with a tensile breaking strength in the machine direction (MD) of 281 MPa, a tensile breaking strength in the transverse direction (TD) of 244 MPa, that is, the sum of these being 525 MPa, the ratio of the tensile breaking strength in the TD to that in the MD being 0.87, a tensile breaking elongation in the MD of 112%, and a tensile breaking elongation in the TD of 139% was used.

[0110] As the stretched nylon film, one with a tensile breaking strength in the MD of 285 MPa, a tensile breaking strength in the TD of 325 MPa, that is, the sum of these being 610 MPa, a tensile breaking elongation in the MD of 170%, a tensile breaking elongation in the TD of 100%, a hot water shrinkage rate in the MD of 3.5%, and a hot water shrinkage rate in the TD of 4.0% was used.

[0111] A laminate 1 for the outer package of the power storage device was produced in the same manner as in Example 1 except that the above materials were used.

[0112] <Example 5> As the stretched polyethylene terephthalate (PET) film, one with a tensile breaking strength in the MD of 306 MPa, a tensile breaking strength in the TD of 279 MPa, that is, the sum of these being 585 MPa, the ratio of the tensile breaking strength in the TD to that in the MD being 0.91, a tensile breaking elongation in the MD of 110%, and a tensile breaking elongation in the TD of 117% was used.

[0113] As the stretched nylon film, one with a tensile breaking strength in the MD of 276 MPa, a tensile breaking strength in the TD of 320 MPa, that is, the sum of these being 596 MPa, a tensile breaking elongation in the MD of 120%, a tensile breaking elongation in the TD of 110%, a hot water shrinkage rate in the MD of 3.4%, and a hot water shrinkage rate in the TD of 4.2% was used.

[0114] A laminate 1 for the outer package of the power storage device was produced in the same manner as in Example 1 except that the above materials were used.

[0115] <Example 6> As the stretched polyethylene terephthalate (PET) film, one with a tensile breaking strength in the machine direction (MD) of 240 MPa, a tensile breaking strength in the transverse direction (TD) of 260 MPa, that is, the sum of these is 500 MPa, a ratio of the tensile breaking strength in the TD to the tensile breaking strength in the MD of 1.08, a tensile breaking elongation in the MD of 140%, and a tensile breaking elongation in the TD of 120% was used.

[0116] As the stretched nylon film, one with a tensile breaking strength in the MD of 250 MPa, a tensile breaking strength in the TD of 280 MPa, that is, the sum of these is 530 MPa, a tensile breaking elongation in the MD of 120%, a tensile breaking elongation in the TD of 100%, a hot water shrinkage rate in the MD of 2.1%, and a hot water shrinkage rate in the TD of 2.0% was used.

[0117] A laminate 1 for an outer package of an electric storage device was produced in the same manner as in Example 1 except that the above-mentioned materials were used.

[0118] <Comparative Example 1> As the stretched polyethylene terephthalate (PET) film, one with a tensile breaking strength in the MD of 230 MPa, a tensile breaking strength in the TD of 240 MPa, that is, the sum of these is 470 MPa, a ratio of the tensile breaking strength in the TD to the tensile breaking strength in the MD of 1.04, a tensile breaking elongation in the MD of 100%, and a tensile breaking elongation in the TD of 90% was used.

[0119] As the stretched nylon film, one with a tensile breaking strength in the MD of 210 MPa, a tensile breaking strength in the TD of 270 MPa, that is, the sum of these is 480 MPa, a tensile breaking elongation in the MD of 100%, a tensile breaking elongation in the TD of 80%, a hot water shrinkage rate in the MD of 2.3%, and a hot water shrinkage rate in the TD of 2.2% was used.

[0120] A laminate 1 for an outer package of an electric storage device was produced in the same manner as in Example 1 except that the above-mentioned materials were used.

[0121] <Comparative Example 2> As the stretched polyethylene terephthalate (PET) film, one with a tensile breaking strength in the machine direction (MD) of 310 MPa, a tensile breaking strength in the transverse direction (TD) of 295 MPa, that is, the sum of these being 605 MPa, the ratio of the tensile breaking strength in the TD to that in the MD being 0.95, a tensile breaking elongation in the MD of 96%, and a tensile breaking elongation in the TD of 85% was used.

[0122] As the stretched nylon film, one with a tensile breaking strength in the MD of 210 MPa, a tensile breaking strength in the TD of 270 MPa, that is, the sum of these being 480 MPa, a tensile breaking elongation in the MD of 100%, a tensile breaking elongation in the TD of 80%, a hot water shrinkage rate in the MD of 2.3%, and a hot water shrinkage rate in the TD of 2.2% was used.

[0123] A laminate 1 for the outer package of a power storage device was produced in the same manner as in Example 1 except for using the above-mentioned materials.

[0124] Each laminate 1 for the outer package of a power storage device produced as described above was evaluated based on the following evaluation method. The tensile breaking strength and the tensile breaking elongation were measured in accordance with JIS K7161-2 (2014).

[0125] <Formability evaluation method> Using a 25-ton press machine manufactured by Amada Co., Ltd., a packaging material for a four-layer battery was subjected to deep drawing forming into a rectangular parallelepiped shape (with R-shaped corners) having a length of 55 mm, a width of 35 mm, and each depth. The test started at a depth of 5 mm and the forming depth was increased by 0.5 mm up to a depth of 7 mm. At each forming depth, at four corner parts of the formed product (with 5 samples) obtained after forming, the presence or absence of pinholes or cracks was confirmed. Furthermore, the number of those without the occurrence of pinholes or cracks at each forming depth was confirmed, and the limit forming height was confirmed.

[0126] The formability was evaluated based on the following criteria. The presence or absence of pinholes or cracks was examined by the light transmission method in a dark room.

[0127] (Criteria) 「◎」(Qualified)…Those with a forming depth of 7 mm and no pinholes or cracks 「○」(Qualified)…Those with a forming depth of 6 mm and no pinholes or cracks 「×」(Unqualified)…Those with a forming depth of 6 mm and pinholes or cracks The above results are shown in Table 1.

[0128]

Table 1

[0129] In Table 1, "PET" is oriented polyethylene terephthalate, "ONY" is oriented nylon, and "CPP" is unoriented polypropylene.

[0130] Also, "AL foil" in Table 1 is aluminum foil, and as the AL foil, 8000 series alloy foils with good formability (A8021H-O, A8079H-O: JIS H4160) can be used.

[0131] As is clear from Table 1, it can be seen that sufficient formability is obtained in Examples 1 to 6.

[0132] On the other hand, it can be seen that sufficient formability is not obtained in Comparative Examples 1 and 2.

Industrial Applicability

[0133] The laminate for the outer packaging material of the power storage device of the present invention can be used for portable electronic devices such as smartphones and tablets, hybrid vehicles and electric vehicles, batteries for power generation and night-time power storage (such as lithium-ion secondary batteries and all-solid-state batteries), and capacitors such as lithium ions and electric double-layer capacitors.

Explanation of Reference Numerals

[0134] 1: Laminate for the outer packaging material of the power storage device 2: Substrate layer 21: Polyester film layer 22: Polyamide film layer 3: Barrier layer 4: Sealant layer 5: Adhesive layer between substrates

Claims

1. A metal barrier layer, a base material layer made of a heat-resistant resin laminated on the outer surface of the barrier layer, and a sealant layer made of a heat-sealable resin laminated on the inner surface of the barrier layer, wherein the laminate for an outer package of a power storage device comprises: the base material layer is composed of a polyester film layer as an outer layer and a polyamide film layer as an inner layer, the polyester film layer has a sum of the tensile breaking strength in the MD direction and the tensile breaking strength in the TD direction of 500 MPa to 600 MPa, a ratio of the tensile breaking strength in the TD direction to the tensile breaking strength in the MD direction of 0.8 to 1.1, and the tensile breaking elongation in the MD direction and the tensile breaking elongation in the TD direction of 110% to 200%, and the laminate for an outer package of a power storage device is characterized thereby. However, MD: Machine flow direction, TD: Direction orthogonal to MD

2. The laminate for an outer package of a power storage device according to Claim 1, wherein the polyamide film layer has a hot water shrinkage rate at 100 ° C. for 30 minutes in the MD direction and a hot water shrinkage rate at 100 ° C. for 30 minutes in the TD direction of 2.5% to 6%.

3. The laminate for an outer package of a power storage device according to Claim 1 or 2, wherein the polyamide film layer has a sum of the tensile breaking strength in the MD direction and the tensile breaking strength in the TD direction of 550 MPa to 700 MPa, and the tensile breaking elongation in the MD direction and the tensile breaking elongation in the TD direction of 90% to 200%.

4. An adhesive layer between the base materials is laminated between the polyester film layer and the polyamide film layer, and the laminate for an outer package of a power storage device according to Claims 1 to 3, wherein the adhesive layer between the base materials has a Young's modulus of 70 MPa to 400 MPa, a breaking strength of 20 MPa to 70 MPa, and a breaking elongation of 50% to 400%.

5. The laminate for an outer package of a power storage device according to Claim 4, wherein the adhesive layer between the base materials is composed of a cured product of an adhesive mainly composed of one or more resins selected from a polyurethane-based resin, a polyester polyurethane-based resin, a polyether polyurethane-based resin, a polyether-based resin, and a polyester-based resin and a polyfunctional isocyanate as a curing agent.

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