JP2016081705A - Laminate film for battery outer packaging and battery - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a laminate film for battery outer packaging which is high in seal strength and inter-layer bonding strength, superior in heat resistance, electrolyte resistance, and adhesiveness with a tab-seal layer and less in load on an environment, and which can be manufactured inexpensively.SOLUTION: A laminate film 10 for battery outer packaging comprises at least a base material layer 1, a first adhesion layer 2, a barrier layer 3, a second adhesion layer 4 and a sealant layer 5 which are laminated in this order. The sealant layer 5 has at least one (I) layer formed by a blend arranged by mixing polyethylene of a density of 0.930-0.950 g/cmand manufactured by use of a metallocene-based catalyst with a polypropylene-based elastomer including a polypropylene matrix and rubber dispersed in the polypropylene matrix.SELECTED DRAWING: Figure 1

Description

  The present invention relates to a laminate film for battery exterior. More specifically, the present invention relates to a battery body having a liquid, gel polymer, or solid electrolyte in a battery such as a lithium battery (lithium primary or secondary battery), a lithium ion secondary battery, or a polymer battery. The present invention relates to a laminate film for battery exterior packaging. The present invention also relates to a battery using the laminate film for battery exterior.

  In recent years, lithium batteries, lithium ion secondary batteries, and the like have been developed as thin and small batteries used in mobile phones, personal computers, automobiles, and the like. Conventionally, a metal can type has been used as an exterior material of these batteries. However, in recent years, since the degree of freedom in design of the battery is high and the weight can be further reduced, the base material layer and the sealant layer are used. A polymer film is used for the barrier layer, a metal foil is used for the barrier layer, and a laminated film of the base material layer / barrier layer / sealant layer formed by laminating them together, and the sealant layers are heat sealed to form a bag or a case What has been processed to have been used.

Some battery exterior materials are called pouch type or embossed type depending on the packaging form of the battery body. The pouch type is a three-side seal, four-side seal, pillow type, or other bag-shaped type. On the other hand, the embossed type has a recess in one or both exterior materials, and the battery body is stored in this recess. There is a shape in which the buttocks are sealed by heat sealing.
The battery exterior laminate film constituting these battery exterior materials requires high sealing strength as a basic packaging member and strong puncture resistance against external stress, but for the following reasons: There is also a demand for excellent anti-electrolytic solution resistance, high sealing properties and interlayer adhesion in a high temperature environment.

That is, in a lithium battery, together with a positive electrode material and a negative electrode material as battery contents, a polar solvent such as ethylene carbonate, propylene carbonate, dimethyl carbonate, diethyl carbonate, and ethyl methyl carbonate as an electrolyte solution, and LiPF ₆ and LiBF ₄ as electrolytes. What mix | blended lithium salts, such as these, is used. Since these electrolyte solvents have high penetrability into the polymer film, the adhesive strength of the seal portion decreases due to penetration of the solvent of the electrolyte into the laminated film of the exterior material, and the adhesive strength between the layers. Decline is a problem.
Furthermore, in the battery, a hydrolytic reaction occurs between a slight amount of moisture contained in the electrode, active material, electrolyte, etc., moisture entering from the outside through the cross section of the seal layer, and lithium salt of the electrolyte. Produces. This hydrofluoric acid penetrates into the sealant layer of the laminated film of the exterior material and causes metal corrosion of the barrier layer, further promoting the decrease in the adhesion between the sealant layer and the barrier layer and the decrease in the adhesive strength of the seal part. Will be allowed to.
In addition, the lithium battery is assumed to have been left in a car in midsummer, and even when left in a high temperature environment at 60 to 80 ° C., it needs heat resistance to maintain the sealing strength and the adhesive strength between the layers. It becomes.

  For this reason, the laminated film as a battery outer packaging material is required to be much better than other packaging materials in terms of the sealability between sealant layers and the adhesive strength between layers. Is done.

  Conventionally, in order to impart corrosion resistance to hydrofluoric acid generated from the electrolyte, aluminum foil used for the barrier layer is surface treated, and various polypropylene and polyethylene are used as the constituent material of the sealant layer. ing.

  As for the sealant layer, the one using polypropylene in terms of heat resistance has been the mainstream, but since polypropylene has a problem with the electrolytic solution resistance and seal strength, in recent years, it has a sealant layer using polyethylene. Investigations are being made on sealants for battery packaging.

  For example, Patent Document 1 discloses a laminate composed of a base material layer, an adhesive layer 1, a barrier layer, an adhesive layer 2, and a sealant layer, wherein the sealant layer includes a metallocene-based linear low-density polyethylene. A battery packaging material in which at least one layer is laminated is proposed.

  Patent Document 2 proposes a sealant layer having a multilayer structure containing medium density polyethylene, and discloses a sealant layer obtained by blending medium density polyethylene and linear low density polyethylene.

  Patent Document 3 discloses that an adhesive resin layer and a sealant layer are formed by coextrusion, and the sealant layer is a metallocene catalyst-based linear low density polyethylene.

  Patent Document 4 discloses that the adhesive resin layer is acid-modified polyethylene, the innermost resin layer is a medium density polyethylene having a density of 0.935 or more, and MFR (melt flow rate) 1 to 10 g / 10 min, and the adhesive resin layer and the innermost resin. A packaging material for a lithium battery is disclosed in which the layer is a layer formed by coextrusion.

  Patent Document 5 proposes a battery packaging material having a multilayer structure in which the sealant layer includes a high-density polyethylene layer, and among them, a sealant layer in which high-density polyethylene and linear low-density polyethylene are blended is disclosed. .

Japanese Patent Laid-Open No. 2003-1000026 JP 2003-36822 A JP 2003-272570 A JP 2002-93386 A JP 2003-36821 A

  In a laminate having a sealant layer in which at least one resin layer containing a metallocene-based linear low-density polyethylene described in Patent Document 1 is laminated, since there is one resin layer having a low density, from the moisture in the electrolyte solution There is a problem that the generated hydrogen fluoride is easily transmitted, and the aluminum of the barrier layer is corroded to easily cause delamination. In addition, the sealing strength is not sufficient and is often not suitable as a battery packaging material. In addition, there is a drawback that the adhesiveness of the sealing member used for sealing with the electrode tab to the polypropylene resin, that is, the adhesiveness to the tab seal layer is inferior. Furthermore, the melting point of linear low density polyethylene is as low as 120 ° C., and there is a problem with heat resistance.

  The laminate having a sealant layer obtained by blending medium density polyethylene and linear low density polyethylene described in Patent Document 2 has a problem in adhesiveness to the polypropylene resin of the sealing member, that is, adhesiveness to the tab seal layer. Also, as in Patent Document 1, there is a problem with heat resistance.

  A laminate having a sealant layer obtained by co-extrusion of a metallocene-based linear low-density polyethylene described in Patent Document 3 has a problem that the electrolyte solution permeability of the low-density polyethylene resin layer is high as in Patent Document 1. In addition, low density polyethylene does not have sufficient sealing strength and has a problem with heat resistance. Furthermore, there is also a problem that the adhesiveness of the tab seal layer to the polypropylene resin is inferior.

  The laminate having a sealant layer mainly composed of medium density polyethylene having a density of 0.935 or more and MFR of 1 to 10 g / 10 min described in Patent Document 4 has a problem in adhesiveness with a tab seal layer made of polypropylene resin. There is also a problem with heat resistance.

  The laminate having a sealant layer obtained by blending high-density polyethylene and linear low-density polyethylene described in Patent Document 5 has a problem in terms of adhesion and heat resistance with a tab seal layer made of a polypropylene resin.

  As described above, various types of laminated films for battery exterior materials using a polyethylene-based resin as a sealant layer have been proposed, but sealing properties as packaging materials, adhesiveness with a tab-seal layer made of polypropylene-based resin, and electrolysis resistance A laminated film having both liquid and heat resistance has not been obtained.

  The present invention solves the above-mentioned problems, and the object of the present invention is to provide high sealing strength and interlayer adhesion strength, excellent electrolytic solution resistance and heat resistance, and excellent adhesiveness with the tab seal layer, and the environment. An object of the present invention is to provide a laminate film for battery exterior that can be manufactured at low cost by a method with less load.

The present inventors have a result of intensive studies, as a material constituting the sealant layer, the component (A): Density was prepared using a metallocene catalyst 0.930 g / cm ³ or more 0.950 g / cm ³ to less polyethylene Component (B): A laminate film for battery exterior having excellent resistance to electrolyte, adhesion to the tab seal layer, and heat resistance is provided by blending and using a polypropylene elastomer in which rubber is dispersed in a polypropylene matrix. It was found that the sealing strength can be further increased by further including the component (C): ethylene-1-octene block copolymer.

  The present invention has been achieved based on such findings, and the gist thereof is as follows.

[1] A laminate film for battery exterior in which at least a base material layer, a first adhesive layer, a barrier layer, a second adhesive layer, and a sealant layer are laminated in this order, and the sealant layer includes the following components ( A laminate film for battery exterior, comprising at least one layer (I) formed of a blend comprising A) and the following component (B).
Component (A): Density was prepared using a metallocene catalyst 0.930 g / cm ³ or more 0.950 g / cm ³ or less polyethylene component (B): polypropylene elastomer rubber in a polypropylene matrix is dispersed

[2] The laminate film for battery exterior according to [1], wherein the compound constituting the layer (I) further contains a component (C): an ethylene-1-octene block copolymer.

[3] The composition constituting the layer (I) comprises 20% to 80% by weight of the component (A), 5% to 55% by weight of the component (B), and the component (C). 5 to 55% by weight of the laminate film for battery exterior as set forth in [2].

[4] The battery exterior laminate as described in any one of [1] to [3], wherein the barrier layer is made of an aluminum foil having a boehmite film formed on at least the surface on the liquid contact surface side. the film.

[5] A battery comprising the laminate film for battery exterior according to any one of [1] to [4].

ADVANTAGE OF THE INVENTION According to this invention, the sealing film and the interlayer adhesive strength are high, while being excellent in electrolyte solution resistance and heat resistance, the laminated film for battery exteriors which was excellent also in adhesiveness with a tab seal layer is provided. In addition, the laminate film for battery exterior of the present invention can be manufactured at low cost by a method with less environmental load.
By using the laminate film for battery exterior according to the present invention, the battery can be reduced in weight, thickness, size, cost, long-term durability, and reliability.

It is sectional drawing which shows embodiment of the laminate film for battery exteriors of this invention. It is the schematic of the thermal lamination process which shows an example of the manufacturing method of the laminated film for battery exteriors of this invention. It is a perspective view which shows an example of the battery exterior material using the laminate film for battery exteriors of this invention.

Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings.
FIG. 1 is a cross-sectional view showing an embodiment of a laminate film for battery exterior of the present invention, and FIG. 2 is a schematic view of a thermal lamination process showing an example of a method for producing a laminate film for battery exterior of the present invention. 3 is a perspective view showing an example of a battery exterior material using the laminate film for battery exterior of the present invention. However, FIGS. 1-3 shows an example of embodiment of this invention, The laminate film for battery exteriors of this invention, and a battery exterior material are not limited to what is shown in FIGS. . Moreover, the manufacturing method of the laminate film for battery exteriors of this invention is not limited to what passes through the thermal lamination process shown in FIG.

In this specification, the tensile modulus of the resin or resin composition is measured at 1 mm / min with a Tensilon-type tensile tester using a strip-like sample with a width of 15 mm based on ISO 1184-1970 with a distance between chucks of 100 mm. Value. Further, MFR (melt flow rate) is measured at 190 ° C. and 2.16 kgf load in the case of polyethylene resin, acid-modified polyethylene resin or a resin composition containing these as a main component based on JIS K7210A method. In the case of a polypropylene resin or a polypropylene resin composition, it is a value measured at 230 ° C. and a 2.16 kgf load. The density of the resin is determined by the JISK7112A method (submerged substitution method).
The melting point is obtained from the melting end temperature when measured with a DSC (differential scanning calorimeter) at a heating rate of 10 ° C./min.

[Laminate film for battery exterior]
As shown in FIG. 1, the laminate film 10 for battery exterior of the present invention has at least a base layer 1, a first adhesive layer 2, a barrier layer 3, a second adhesive layer 4, and a sealant layer 5 laminated in this order. is made, the sealant layer 5, the component (a): and 0.950 g / cm ³ or less of polyethylene manufactured density 0.930 g / cm ³ or more by using a metallocene catalyst, component (B): polypropylene matrix It is characterized by having at least one layer (I) formed of a blend containing a polypropylene-based elastomer in which rubber is dispersed.

<Base material layer>
The base material layer 1 in the present invention reinforces the barrier layer 3 to prevent damage to the barrier layer 3 due to external force due to piercing or the like, and the battery outer laminate film itself during processing of the battery outer laminate film. It is a layer for preventing breakage and may be a single layer or a laminate of two or more layers.
The base material layer 1 is required to be excellent in mechanical strength and heat resistance, and is preferably made of a resin film having a high tensile elastic modulus.

  Preferred resins used for the base material layer 1 include polyamide (PA), polyamideimide (PAI), polyimide (PI), polyacetal (POM), polyarylate (Par), polycarbonate (PC), polyethylene terephthalate (PET), Polyalkylene terephthalate (PAT) such as polybutylene terephthalate (PBT), polytrimethylene terephthalate (PTT), polyethylene naphthalate (PEN), polybutylene naphthalate (PBN), polymethyl methacrylate (PMMA), polyphenylene oxide (PPE) , Polyethersulfone (PES), polymethylpentene (PMP), polyoxybenzylene (POB), liquid crystalline polyester, polysulfone (PSF), polyphenylene sulfide (PP) ), Poly bisamide triazole, polyaminobismaleimide, polyether imide (PEI), 1 kind or a mixture of two or more of these thermoplastic resins such as polyetheretherketone (PEEK) and the like.

  Among these, polycarbonate (PC), polybutylene terephthalate (PBT), polyalkylene terephthalate (PAT) such as polyethylene terephthalate (PET), polyethylene naphthalate (PEN), polybutylene naphthalate (PBN), polyamide (PA), Polyphenylene sulfide (PPS), polyamideimide (PAI), and polyimide (PI) are preferable.

  Although the base material layer 1 may be an unstretched film or a stretched film, it is preferably a stretched film from the viewpoint of mechanical strength and heat resistance, and particularly preferably a biaxially stretched film. In particular, a biaxially stretched polyethylene terephthalate film, a biaxially stretched polyethylene naphthalate film or a biaxially stretched polyamide film is preferable because it has a high tensile elastic modulus and is inexpensive.

  The base material layer 1 has a role for preventing pinhole generation of the barrier layer 2 due to deformation such as external piercing during assembly as a battery, and press processing generally performed when pouching or embossing. In order to play a role in preventing damage to the laminate film for battery exterior during the overhanging process, a certain degree of elastic modulus and thickness are required.

  The tensile elastic modulus of the base material layer 1 is usually 2000 MPa or more, preferably 2200 MPa or more, and particularly preferably 2400 MPa or more. The upper limit of the tensile elastic modulus is not particularly defined, but the tensile elastic modulus of the preferred resin as described above is usually 6000 MPa or less.

  Moreover, the thickness of the base material layer 1 is preferably 10 μm or more and 50 μm or less. When the thickness of the base material layer 1 is larger than 50 μm, the laminate film for battery exterior becomes too high in rigidity and not only is difficult to process such as press working, but also the surface density tends to increase and the weight cannot be reduced. . Moreover, when the thickness of the base material layer 1 is less than 10 μm, the puncture resistance may be affected. The thickness of the base material layer 1 is particularly preferably 12 μm or more and 30 μm or less.

  When the battery exterior laminate film is an embossed exterior material as illustrated in FIG. 3, the base material layer 1 also needs to be slidable with the mold during press molding. It is preferable to improve the slipperiness by applying a lubricant to the surface (the outermost surface of the laminate film for battery exterior) or providing unevenness.

  However, when a lubricant is used, there is a concern about the problem of mold contamination due to the lubricant. Therefore, it is particularly preferable that the surface of the base material layer 1 is uneven to reduce the coefficient of friction with the mold. . In this case, the unevenness of the surface of the base material layer 1 is a surface measured in an area of 40 μm × 40 μm using a laser microscope VK8500 manufactured by Keyence Co., Ltd. under the measurement conditions of lens 100 times, pitch 0.01 μm, shutter speed AUTO, gain 835. The average value obtained by measuring the roughness Ra at four points is preferably 0.3 μm or more and 1.0 μm or less. If Ra is smaller than the lower limit, the slipping property tends to be insufficient, and if Ra is larger than the upper limit, dust tends to adhere to the unevenness. A preferable surface roughness Ra of the base material layer 1 is not less than 0.35 μm and not more than 0.70 μm.

<First adhesive layer>
The first adhesive layer 2 is a layer for adhering the base material layer 1 and the barrier layer 3. When the base material layer 1 and the barrier layer 3 are bonded together by a dry lamination method, the first adhesive layer 2 is used for dry lamination. Adhesive, for example, aliphatic polyester, aromatic polyester, polyethyleneimine, polyether, cyanoacrylate, urethane, organic titanium, polyetherurethane, epoxy, polyesterurethane, imide, isocyanate Various adhesives such as those based on polyolefin, polyolefin, silicone, and acrylic can be used.
Among these adhesives, aromatic polyester-based, polyolefin-based, and acrylic-based adhesives are preferable because of their excellent resistance to electrolytic solution.

  When further electrolytic solution resistance is required, the base material layer 1 and the barrier layer 3 may be bonded together by a thermal lamination method using an acid-modified resin film for the first adhesive layer 2.

  Although the thickness of the 1st contact bonding layer 2 is not limited, Usually, it is about 1-10 micrometers.

<Barrier layer>
The barrier layer 3 is a layer for preventing (barrier) the entry of moisture from the outside into the battery, has no pinhole, and has a high tensile strength as a laminate film for battery exterior. It is required to have crack resistance against deformation and elongation during embossing and pouching.

As the barrier layer 3, a metal foil (metal layer) is preferable, and an aluminum foil is particularly preferable. Further, from the viewpoint of crack resistance during press working or embossing, an aluminum foil excellent in extensibility is preferable, and an aluminum foil containing 0.3 wt% or more and 3.0 wt% or less of iron is preferable. If the iron content is less than this range, the elongation tends not to be sufficient. If the iron content is more than this range, the problem of corrosion of the barrier layer 3 due to hydrofluoric acid generated from the electrolytic solution tends to occur. . The preferable iron content of the aluminum foil is not less than 0.5% by weight and not more than 1.7% by weight.
Moreover, although hard aluminum foil and soft aluminum foil exist in aluminum foil, since the soft aluminum foil which performed annealing treatment has a softness | flexibility, it is preferable.

The thickness of the barrier layer 3 such as an aluminum foil is preferably 9 μm or more and 60 μm or less, and particularly preferably 20 μm or more and 50 μm or less in order to achieve both thinning and barrier properties.
In addition, although the metal foil (metal layer) shape | molded previously is normally used for the barrier layer 3, the aspect which forms the barrier layer 3 by a vapor deposition method or the apply | coating method is also included, for example.

<Surface treatment of aluminum foil>
A surface treatment of an aluminum foil suitable as a barrier layer in the present invention is not necessarily required, but a surface treatment for imparting corrosion resistance may be performed.

  When surface treatment is performed on an aluminum foil as a barrier layer, a known treatment is used as the surface treatment. For example, chromate chromate treatment, phosphoric acid chromate treatment, phosphoric acid-chromate treatment, chromate treatment, alkali Examples thereof include chromium-based chemical conversion treatment such as chromate treatment and coating-type chromate treatment, coating-type non-chromium treatment such as zirconium, titanium, and zinc phosphate, boehmite treatment, and anodizing treatment. In addition to these treatments, corona treatment, plasma treatment, flame treatment, and other treatments for imparting polar groups to the surface of the aluminum foil are performed to enhance corrosion resistance by enhancing adhesion to the second adhesive layer. May be. Two or more of these processes may be combined.

Among the above surface treatments, boehmite treatment that has a low environmental burden and can be surface treated at low cost is preferable.
The boehmite treatment is a treatment for forming an aluminum hydrated oxide film (boehmite film) having a boehmite crystal structure on the surface of the aluminum foil by holding the aluminum foil in high-temperature boehmite-treated water for a certain period of time.

  The preferred boehmite-treated water contains deionized water and an alkali such as triethanolamine and ammonia in an amount of 0.1 wt% to 2 wt%, preferably 0.3 wt% to 1 wt%, more preferably 0. The boehmite treatment is performed by heating such boehmite-treated water to 90 to 100 ° C., and the aluminum foil for 20 seconds to 5 minutes, preferably 20 seconds. It can be performed by immersing for 1 minute.

  By such boehmite treatment, the thickness is preferably 0.1 μm or more and 1 μm or less, more preferably 0.1 μm or more and 0.8 μm or less, and still more preferably 0.2 μm or more and 0. If the aluminum foil is formed with a boehmite film of 4 μm or less, strong adhesiveness is obtained in heat lamination with an acid-modified polyethylene resin layer, which will be described later, which is preferably used as the second adhesive layer, and it has excellent resistance to electrolyte. It can be set as the laminated film for battery exterior. If the thickness of the boehmite film is thinner than the above range, the effect of improving the adhesiveness by the boehmite treatment cannot be sufficiently obtained, and if it is thicker than the above range, the boehmite crystal is easily detached from the interface with the aluminum foil, which is not preferable .

<Sealant layer>
In addition to the heat resistance required for batteries and interlayer adhesion as a laminated film, the sealant layer 5 has heat sealability during processing as a battery exterior material, resistance to electrolyte, and adhesion to electrode tabs. In order to enhance the property, adhesion with a tab seal layer (usually a single layer or a laminated film of various polyethylenes or polypropylenes) wound around the electrode tab is required.
Sealant layer 5 in the present invention, component (A): a density of 0.930 g / cm ³ or more 0.950 g / cm ³ or less of polyethylene produced using a metallocene catalyst, component (B): a rubber in a polypropylene matrix And (I) layer formed of a blend containing a component (C): ethylene-1-octene block copolymer.
In addition, in this invention, if the compound which forms said (I) layer contains said component, it may contain the other component.
Further, the sealant layer 5 may have a single-layer structure composed of only the above-mentioned (I) layer, and a multilayer of two or more layers of this (I) layer and other layers within a range not impairing the effects of the present invention. It may be a structure. Further, the sealant layer 5 may have at least one layer (I) and may have two or more layers.

Polyethylene is generally classified according to its density. Density of 0.910 g / cm ³ or more and less than 0.930 g / cm ³ is low density polyethylene (LDPE), and density of 0.942 g / cm ³ or more is high density polyethylene (HDPE). Called. The ethylene to have a variety of α- olefins partially copolymerized, referred to as a density 0.910 g / cm ³ or more 0.925 g / cm ³ less than those of the linear low density polyethylene (LLPE). Although all polyethylene has a lower melting point than polypropylene, it is a polymer whose molecules are cross-linked by repeated application of heat, and for long-term exposure in a high-temperature environment of 80 to 90 ° C. required for battery exterior materials. It is difficult to cut molecules and has better long-term heat resistance than polypropylene.

  Furthermore, polyethylene has a high melt tension, flexibility, resistance to deformation when processed as a battery exterior material, hardly whitening during deformation, and excellent cold resistance. In addition, polyethylene has a higher density than polypropylene and has high resistance to moisture from the outside and a carbonate-based solvent that is a polar solvent for the electrolytic solution.

The (I) layer according to the present invention has moderate flexibility among the polyethylene excellent in various properties as described above, and has excellent adhesiveness with a polypropylene tab seal layer that is wound around the electrode tab. from as component (a), the density was produced using a metallocene catalyst 0.930 g / cm ³ or more 0.950 g / cm ³ or less of polyethylene (hereinafter sometimes referred to as "metallocene polyethylene".) the Use.
Polyethylene polymerized using a metallocene catalyst exhibits a very narrow molecular weight distribution compared to polyethylene polymerized using a common catalyst (Ziegler-Natta catalyst), and the distribution of comonomer is also uniform. Among the required properties of the layer, it is particularly adaptable to electrolyte resistance.

However, when the sealant layer is composed of a general metallocene linear low density polyethylene having a low density, the adhesive property of the tab seal material with polypropylene is preferable in that it is superior to other polyethylene resins. As a result, further improvement was necessary. Further, a sealant layer composed only of a general metallocene linear low-density polyethylene having a low density has problems in seal strength and heat resistance.
Therefore, in the present invention, component (B): polypropylene which is excellent in miscibility with polyethylene of component (A) and which can effectively improve the heat resistance, seal strength and electrolyte resistance of component (A). A blend of a polypropylene-based elastomer in which rubber is dispersed in a matrix (hereinafter sometimes referred to as “rubber-dispersed polypropylene-based elastomer”) is used as a main component of the blend forming the (I) layer.
As used herein, the main component refers to a component that is contained most in a weight ratio in a material obtained by blending a plurality of components.
When a rubber-dispersed polypropylene elastomer is compounded and used in a metallocene polyethylene, a rubber-dispersed polypropylene elastomer in the presence of the metallocene polyethylene is formed into a layered morphology in the presence of the metallocene polyethylene, The metallocene polyethylene has both an electrolyte solution resistance and a heat resistance of polypropylene, and the molecular chain and branched side chain of the metallocene polyethylene are not only of the polyethylene but also of a molecule derived from a rubber-dispersed polypropylene elastomer. Entangling can be easily caused, and the adhesion between the sealant layers, the sealant layer and the second adhesive layer, and the sealant layer and the tab seal layer can be enhanced.

  In the present invention, the metallocene polyethylene may be a copolymer of ethylene and an α-olefin having about 4 to 20 carbon atoms. Specific examples of the branched side chain composed of the α-olefin include butene- Examples include various comonomers such as 1, hexene-1, 4-methylpentene-1, octene-1, decene-1, tetracene-1, and octadecene-1. Two or more of these α-olefins may be used in combination. Further, if an α-olefin having about 4 to 20 carbon atoms is used as a comonomer, propylene may be further used as a comonomer.

When the density of the component (A) metallocene polyethylene is less than 0.930 g / cm ³ , the density is too low and the electrolytic solution resistance is inferior, and when the density is higher than 0.950 g / cm ³ , it becomes brittle and seal strength Is lacking. To achieve both sealing strength and electrolytic solution resistance, the density of the metallocene polyethylene is required to be 0.930 g / cm ³ or more 0.950 g / cm ³ or less. The density of the metallocene polyethylene is preferably 0.935 g / cm ³ or more and 0.945 g / cm ³ or less, and if it is in this range, the seal strength and the electrolytic solution resistance can be raised to the highest grade, which is preferable.

  The MFR of the metallocene polyethylene is not particularly limited, but is preferably MFR 0.1 g / 10 min or more and less than 10 g / 10 min. Particularly preferred MFR is 0.1 g / 10 min or more and less than 1 g / 10 min, and if the MFR is within this range, the resin melts during heat sealing to prevent a decrease in seal strength due to a decrease in the thickness of the sealant layer. The component (B) is particularly preferable in terms of improving dispersibility with the rubber-dispersed polypropylene elastomer.

On the other hand, as the rubber-dispersed polypropylene elastomer of component (B), in particular, those in which rubber is dispersed in a homopolypropylene matrix are preferable in terms of heat resistance, and among them, the diameter of rubber dispersed particles present in the polypropylene matrix is 1 μm or less. In the presence of metallocene medium density polyethylene, homopolypropylene forms a good layered multilayer morphology in the presence of metallocene medium density polyethylene. Electrolyte resistance and heat resistance due to polypropylene with metallocene medium density polyethylene. It is preferable because it has both.
The particularly preferable rubber dispersed particle diameter of the rubber dispersed polypropylene elastomer is 0.5 μm or less. There is no particular limitation on the lower limit of the rubber dispersed particle size. Here, the rubber dispersed particle size of the rubber-dispersed polypropylene-based elastomer was determined by staining a section prepared by cutting the cross section of the film in a direction perpendicular to the extrusion direction with a strong oxidizing agent such as ruthenium tetroxide, and using a transmission electron microscope. The value obtained from the shorter diameter when observed with

  In addition, the rubber content of the rubber-dispersed polypropylene elastomer is preferably 30% by weight or more in order to enhance flexibility and improve interlayer adhesion as a laminated film. In particular, when a rubber-dispersed polypropylene elastomer having a high rubber content with a rubber content of 40% by weight or more is used, the above-mentioned (I) layer constituting the blend is formed of a metallocene-based rubber layer derived from the rubber-dispersed polypropylene elastomer. A polyethylene component enters, a morphology in which the polyethylene layer and the polypropylene layer become sufficiently thick is formed, and a structure having further excellent electrolytic solution resistance and heat resistance is preferable. However, a rubber-dispersed polypropylene elastomer having an excessively high rubber content tends to bleed at a low density and impairs the electrolytic solution resistance. Therefore, the rubber content of the rubber-dispersed polypropylene elastomer is usually 70% by weight or less.

  Rubber dispersed in the rubber-dispersed polypropylene elastomer includes ethylene-propylene copolymer, ethylene-butene copolymer, propylene-butene copolymer, ethylene-butene-propylene copolymer, ethylene-propylene-diene copolymer. Ethylene-based elastomers such as polymers are preferred in terms of dispersibility and bonding properties with rubber-dispersed polypropylene-based elastomers such as polypropylene and metallocene-based polyethylene. The rubber-dispersed polypropylene-based elastomer may include only one kind of the above rubber, or may include two or more kinds.

The MFR of the component (B) rubber-dispersed polypropylene elastomer is preferably from 0.1 g / 10 min to 10 g / 10 min from the viewpoint of dispersibility with the metallocene polyethylene of the component (A), more preferably 0.5 g / 10 min to 3 g / 10 min. As much as possible, it is preferable from the viewpoint of dispersibility that the MFRs of the components (A) and (B) are the same. Further, it is preferable that the density of the rubber dispersion polypropylene elastomer is less than 0.850 g / cm ³ or more 0.900 g / cm ^3.

The compound forming the layer (I) is composed of the metallocene polyethylene of the component (A) in terms of obtaining good inflation molding stability, heat resistance, electrolytic solution resistance, and adhesiveness with a polypropylene tab seal layer. It is preferable that the rubber-dispersed polypropylene elastomer of component (B) is contained in a proportion of 5% by weight to 60% by weight. This blending ratio is preferable in that the block structure of ethylene and propylene can be maintained in a layered form, and the heat resistance and electrolytic solution resistance are improved.
Particularly preferred blending ratios are component (A): metallocene polyethylene 50 wt% to 90 wt%, and component (B): rubber-dispersed polypropylene elastomer 10 wt% to 50 wt%.

The compound which forms the said (I) layer may contain components other than the said component (A) and a component (B), for example, polyethylene resins other than a metallocene polyethylene, and a polypropylene resin. Specifically, high density polyethylene (HDPE), medium density polyethylene, low density polyethylene (LDPE), random polypropylene (R-PP), block polypropylene (B-PP), homopolypropylene (H-PP), etc. are blended. be able to.
Further, ethylene-propylene copolymer, ethylene-butene copolymer, ethylene-1-octene copolymer, propylene-butene copolymer, ethylene-butene-propylene copolymer, ethylene-propylene-diene copolymer, etc. These olefin elastomers may be further blended.
In particular, it is preferable to blend a polyethylene elastomer in addition to the component (A) and the component (B). Examples of the polyethylene elastomer include ethylene-propylene copolymer, ethylene-butene copolymer, and ethylene-butene. -Propylene copolymer, ethylene-propylene-diene copolymer, ethylene-1-octene copolymer and the like are preferred, and particularly when component (C): ethylene-1-octene block copolymer is blended. The binding effect between the component (A) metallocene polyethylene and the component (B) rubber-dispersed polypropylene elastomer, which is a rubber component, is manifested as a result of increased binding between the molecular chain and a stronger seal. Strength can be obtained, which makes polyethylene component and polypropylene component Dispersed in layers, and the layers are firmly bonded without canceling each other's good properties, that is, heat resistance due to the polypropylene component of the rubber-dispersed polypropylene elastomer, and the electrolyte resistance of the metallocene polyethylene, ethylene- This is particularly preferable because a high-strength sealing property with a 1-octene block copolymer can be obtained. In addition, the tension at the time of melting is increased, whereby the film forming property at the time of inflation molding is stabilized, and the mechanical strength of the resulting film, particularly the sealing strength, is also improved, which is preferable.

The ethylene content of the component (C) ethylene-1-octene block copolymer is preferably 5% by weight or more and 55% by weight or less in that the above effect is effectively exhibited. The MFR of the ethylene-1-octene block copolymer is preferably 0.1 g / 10 min or more and 10 g / 10 min or less, and more preferably 0.5 g / 10 min or more and 3 g / min in order to improve the seal strength. 10 min or less. The density of the ethylene-1-octene block copolymer of the component (C) is preferably 0.850 g / cm ³ or more and 0.910 g / cm ³ or less.

When the compound which forms the said (I) layer contains a component (A), a component (B), and a component (C), the preferable compounding ratio of each component is a component (A): Density 0.930g / cm < ³ >. More than 0.950 g / cm ³ of metallocene polyethylene 20 wt% to 80 wt%, component (B): rubber-dispersed polypropylene elastomer 5 wt% to 55 wt%, component (C): ethylene-1-octene block copolymer 5 are% by weight to more than 55 wt% or less, more preferably, component (a): density 0.930 g / cm ³ or more 0.950 g / cm ³ 70% by weight or less of the metallocene polyethylene 30 wt% or more Component (B): Rubber-dispersed polypropylene elastomer 10 wt% to 50 wt% Component (C): Ethylene-1-octene block copolymer 5 wt% to 50 wt % Or less.
Further, the total content of the rubber component derived from the component (B) and the component (C) in the blend is preferably 10% by weight to 75% by weight, particularly preferably 30% by weight to 70% by weight. .

In the compound which forms the said (I) layer, you may further mix | blend other resin components other than the above in the range which does not impair the effect of this invention. Other resin components include various elastomer components such as styrene elastomers, polyester elastomers, polyamide elastomers, and comonomer other than ethylene and α-olefin such as ethylene-vinyl acetate copolymer and ethylene-vinyl alcohol copolymer. And ethylene resins; propylene resins; vinyl chloride resins, polyamide resins, polyester resins, polycarbonate resins, and the like.
However, when the resin (A), (B), (C) is contained in a large amount as the layer (I), the effect of using the components (A), (B), (C) The resin other than the components (A), (B) and (C) may be contained in a small amount of 20% by weight or less, preferably 15% by weight or less in the layer (I). It is necessary to use it.

  In addition, the composition for forming the layer (I) includes an antioxidant, a heat stabilizer, various plasticizers, a light stabilizer, an ultraviolet absorber, a neutralizer, a lubricant, an antifogging agent, if necessary. Various additives such as an anti-blocking agent, a crosslinking agent, a crosslinking aid, a colorant, a flame retardant, and a dispersant can be added.

  The tensile elastic modulus of the sealant layer is 100 MPa or more because it tends to cause material destruction when an external force such as deformation is applied if too much flexibility is applied. On the other hand, if it becomes too hard, it tends to become brittle. It is preferable that the pressure be 1500 MPa or less because it is easy to peel off from the barrier layer 3 that is in contact with each other. The tensile elastic modulus of the sealant layer is more preferably 130 MPa to 1000 MPa, and particularly preferably 180 MPa to 900 MPa.

In the present invention, the sealant layer 5 has the (I) layer formed of a composition mainly composed of component (A): metallocene polyethylene and component (B): rubber-dispersed polypropylene elastomer. Electrolytic solution resistance and sealability can be improved, but when it is necessary to further improve the adhesiveness with the tab seal layer, at least the part that contacts the sealant layer and the tab seal layer is not limited to a specific acid-modified polyethylene resin or acid-modified polypropylene resin. A layer made of polypropylene resin may be laminated.
Here, with respect to the type of acid used for modification of the polyethylene resin and the modification method, the acid and modification method in the resin constituting the second adhesive layer 4 described later can be similarly employed.
However, acid-modified resins have lower heat resistance than non-acid-modified resins, especially when low molecular weight components are deposited during film formation by the sand lamination method or extrusion lamination method that forms films at high temperatures. There is. When such a layer is used as the innermost layer, that is, a layer that is in direct contact with the electrolytic solution, from the portion where the low molecular weight component is deposited, to the inner layer of hydrofluoric acid generated by the solvent of the electrolytic solution or the hydrolysis of the electrolytic solution This may accelerate the penetration of the electrolyte and may cause a problem in the resistance to the electrolyte. For this reason, this layer laminated on the sealant layer is preferably an acid-modified polyethylene resin having a low modification rate or a polyethylene resin layer that is not acid-modified.
Here, “low modification rate” specifically means a modification rate of 0.1% by weight or less, preferably 0.05% by weight or less.

  Further, the entire sealant layer may have a multilayer structure, and a laminated structure of the above (I) layer and, for example, a random polypropylene layer or a block polypropylene layer may be used. That is, since the (I) layer in the present invention is excellent in adhesiveness with polypropylene resin, it has good adhesiveness with the polypropylene resin tab seal layer used for the electrode tab portion. Is placed between the (I) layer and the second adhesive layer 4 to form a laminated structure, whereby the heat resistance of the sealant layer can be further increased. In addition, in order to obtain good adhesion to the tab seal layer, the above-mentioned compound forming the layer (I) has a layer-adhesion property even when the above-mentioned polypropylene resin layer is disposed in the innermost layer of the sealant layer. There is no problem because it is excellent.

The thickness of the sealant layer 5 is preferably 3 μm or more and 80 μm or less, more preferably 10 μm or more and 60 μm or less, and particularly preferably 12 μm or more and 50 μm or less. If the thickness of the sealant layer 5 is smaller than the above range, the seal strength between the sealant layers may not be sufficiently obtained. If it is thicker than the above range, the film forming property at the time of inflation molding is inferior and the thickness is uniform. In addition, the sealant layer 5 is difficult to melt at the time of thermal lamination, and wrinkles and air entrainment may occur easily.
Also in the case of the sealant layer 5 having a multilayer structure, it is preferable that the total thickness falls within the above range.

  In addition, like the base material layer 1, the sealant layer 5 is formed on the surface (the surface opposite to the second adhesive layer 4) which is the outermost surface of the laminate film for battery exterior in order to improve the slipping property at the time of embossing. It is preferable to provide unevenness because a lubricant having a problem of mold contamination can be dispensed with. In this case, the surface roughness Ra of the unevenness imparting surface of the sealant layer 5 is preferably about 0.02 to 0.08 μm, particularly about 0.03 to 0.07 μm. Here, the surface roughness Ra of the sealant layer 5 is a value measured in the same manner as the surface roughness Ra of the substrate layer 1 described above. This surface irregularity can be imparted by a thermal lamination process described later.

<Second adhesive layer>
The second adhesive layer 4 is a layer for bonding the barrier layer 3 and the sealant layer 5, and the material thereof is not limited, but a polypropylene resin such as random polypropylene, block polypropylene, homopolypropylene, or a resin such as various polyethylenes. In view of the resistance to electrolytic solution, it is preferable to contain a polyethylene resin mainly composed of linear low density polyethylene (LLPE). In particular, the second adhesive layer 4 is made of LLPE. made of polyethylene resin as a main component, at least a portion of the polyethylene resins are acid-modified, and, MFR0.1g / 10min or 3 g / 10min or less, density of 0.920 g / cm ³ or more 0.950 g / cm ³ Hereinafter, the tensile modulus is preferably 100 MPa or more and 1000 MPa or less. Moreover, the 2nd contact bonding layer 4 may contain components other than polyethylene resin.

  As mentioned above, polyethylene resin is a polymer whose melting point is lower than that of polypropylene resin, but is a polymer in which molecules are cross-linked by repeated application of heat, and it is long in a high temperature environment of 80 to 90 ° C. necessary for use as a battery exterior material. It is less susceptible to molecular cleavage with time exposure and has better long-term heat resistance than polypropylene resin.

Furthermore, the polyethylene resin has a high melt tension, flexibility, resistance to deformation when processed as a battery exterior material, hardly whitening at the time of deformation, and excellent cold resistance. In addition, the polyethylene resin has a higher density than the polypropylene resin, and has high resistance to moisture from the outside and a carbonate-based solvent that is a polar solvent of the electrolytic solution.
Such a resin obtained by acid-modifying a polyethylene resin is excellent in adhesion to a metal foil such as an aluminum foil constituting the barrier layer, and has a chromium-based chemical conversion treatment or a phosphorus-based chemical conversion treatment that causes environmental pollution to the aluminum foil. Even if it is not applied, a strong adhesive force can be obtained.

In the present invention, among polyethylene resins, a polyethylene resin mainly composed of linear low density polyethylene (LLPE) is used because it has moderate flexibility and excellent adhesion to a barrier layer such as an aluminum foil. Is preferred.
As used herein, the main component refers to a component that is contained most in a weight ratio in a material obtained by blending a plurality of components.

  In the present invention, the linear low density polyethylene (LLPE) means a copolymer of ethylene and an α-olefin having about 4 to 20 carbon atoms as described above, and is a branched side chain composed of an α-olefin. Specific examples include various comonomers such as butene-1, hexene-1, 4-methylpentene-1, octene-1, decene-1, tetracene-1, and octadecene-1. Two or more of these α-olefins may be used in combination. Further, if an α-olefin having about 4 to 20 carbon atoms is used as a comonomer, propylene may be further used as a comonomer. Among these, linear low density polyethylene having at least one side chain of butene-1, hexene-1, and octene-1 is preferable because it has appropriate flexibility. Although the manufacturing method of linear low density polyethylene (LLPE) is not limited, The well-known method of manufacturing polyolefin resin is employable.

  Polyethylene resin other than linear low density polyethylene (LLPE) can be blended in the polyethylene resin constituting the second adhesive layer 4, and the polyethylene resin other than the linear low density polyethylene (LLPE) is not limited. Specifically, there are high density polyethylene (HDPE), medium density polyethylene, low density polyethylene (LDPE), and the like exemplified as polyethylene resins other than the metallocene polyethylene which is the component (A) in the layer (I) described above. Can be mentioned.

  The polyethylene resin constituting the second adhesive layer 4 preferably includes a polyethylene resin that is at least partially acid-modified. Such an acid-modified polyethylene resin can be produced, for example, by modifying an unsaturated carboxylic acid and / or a derivative thereof into a polyethylene resin by graft polymerization.

  A preferred acid-modified polyethylene resin is an acid-modified polyethylene resin that is a blend of linear low-density polyethylene (LLPE) and high-density polyethylene (HDPE), and the blend material has an LLPE of 50 wt% to 98 wt%. It is preferable that HDPE is 2 wt% or more and 50 wt% or less from the viewpoint of heat resistance and resistance to electrolyte solution penetration. Furthermore, in order to impart inflation molding stability, low density polyethylene (LDPE) may be blended as the third component. In this case, the blending ratio is LLPE 50% to 95% by weight, HDPE 5% to 40% by weight. % Or less, preferably 1% by weight or more and 30% by weight or less of LDPE.

  The unsaturated carboxylic acid and unsaturated carboxylic acid derivative used for acid modification of the polyethylene resin are not particularly limited, and examples thereof include dicarboxylic acids such as maleic acid, fumaric acid, itaconic acid, citraconic acid, and mesaconic acid. Acids; Unsaturated monocarboxylic acids such as acrylic acid, methacrylic acid, crotonic acid; dicarboxylic acid anhydrides such as maleic anhydride, fumaric anhydride, itaconic anhydride, mesaconic anhydride, and derivatives such as amides, imides, esters, etc. Can be mentioned. Among these, maleic acid, maleic anhydride, acrylic acid, and methacrylic acid are preferably used, and maleic anhydride is particularly preferable.

  The method for modifying the polyethylene resin is not particularly limited. For example, a solution method in which a polyethylene resin is dissolved in an organic solvent and reacted with an acid (such as maleic anhydride) in the presence of a radical generator, polyethylene Examples thereof include a melting method in which a resin is heated and melted and reacted with an acid (such as maleic anhydride) in the presence of a radical generator.

The acid-modified polyethylene resin may be linear low-density polyethylene (LLPE), which is the main component, or other polyethylene resins that can be used in combination with this, such as high-density polyethylene (HDPE), Low density polyethylene (LDPE) may be used. Furthermore, an acid-modified polyethylene resin and a non-acid-modified polyethylene resin can be appropriately blended and used.
In the case where other polyethylene resins are used in combination with linear low density polyethylene (LLPE), these polyethylene resins may be acid-modified in a mixed or coexisting state, or at least one of the polyethylene resins may be preliminarily used. It may be used after being acid-modified and a mixture of this and other polyethylene resins not acid-modified.

If the modification rate of the acid-modified polyethylene resin (content of acid groups in the acid-modified polyethylene resin) is too small, the effect of improving adhesiveness due to acid modification may not be obtained sufficiently. Since the heat resistance of the modified polyethylene resin tends to decrease, it is preferably 0.05% by weight or more and 10% by weight or less, particularly preferably 0.2% by weight or more and 5% by weight or less. Here, the modification rate of the acid-modified polyethylene resin can be confirmed by means such as infrared absorption spectrum analysis (IR) or titration. In addition, in the case of blending and using an acid-modified polyethylene resin and a non-acid-modified polyethylene resin, the modification rate refers to the modification rate in all polyethylene resins including a polyethylene resin not acid-modified. Shall mean.
In addition, as an acid-modified polyethylene resin, a commercial item can also be used. For example, it corresponds to the above from Mitsubishi Chemical Corporation, Modic (trade name) series, Mitsui Chemicals, Admer (trade name), etc. What is to be selected can be appropriately selected and used.

  The second adhesive layer 4 may contain a resin other than the polyethylene resin as long as the effects of the present invention are not impaired. The resin other than the polyethylene resin is not limited. For example, an ethylene-based resin obtained by copolymerizing ethylene and a comonomer other than an α-olefin, such as an ethylene-vinyl acetate copolymer or an ethylene-vinyl alcohol copolymer; a propylene-based resin Vinyl chloride resin, polyamide resin, polyester resin, polycarbonate resin and the like. In addition, when the resin other than the polyethylene resin is contained in a large amount as the second adhesive layer 4, since the effect of using the above-described polyethylene resin may be impaired, these resins are used in the second adhesive layer. It is preferable to use in the range of 20% by weight or less, preferably 15% by weight or less.

  Further, the second adhesive layer 4 has an ethylene-propylene copolymer, an ethylene-butene copolymer, a propylene-butene copolymer, and an ethylene-butene-propylene copolymer as long as the effects of the present invention are not impaired. Olefin elastomers such as ethylene-propylene-diene copolymers, various elastomer components such as styrene elastomers, polyester elastomers, polyamide elastomers, antioxidants, thermal stabilizers, various plasticizers, light stabilizers, ultraviolet rays Various additives such as an absorbent, a neutralizing agent, a lubricant, an antifogging agent, an antiblocking agent, a crosslinking agent, a crosslinking aid, a colorant, a flame retardant, and a dispersing agent can be added.

Second adhesive layer, MFR0.1g / 10min or 3 g / 10min or less, density of 0.920 g / cm ³ or more 0.950 g / cm ³ or less, is preferably less than the tensile modulus of 100 MPa 1000 MPa.

  If the MFR of the second adhesive layer 4 is greater than 3 g / 10 min, the fluidity is too high and a flow due to melting of the resin occurs at the time of sealing, and the thickness of the seal portion is insufficient, which may cause a decrease in seal strength. is there. Furthermore, the molecular weight is lowered, the permeability to hydrofluoric acid generated from the electrolytic solution is increased, and the barrier layer may be corroded. The more preferable MFR of the second adhesive layer 4 is 2 g / 10 min or less, more preferably 1.5 g / 10 min or less. The lower limit of the MFR of the second adhesive layer 4 is preferably at least 0.1 g / 10 min since it is preferably at a level that does not cause a problem in film formation when the film is formed by an inflation molding method. .3 g / 10 min or more is preferable because high-speed moldability and high seal strength in inflation molding can be maintained.

In addition, the density of the second adhesive layer 4 is preferably 0.920 g / cm ³ or more. If the density is smaller than this, the solvent resistance and the electrolytic solution resistance may deteriorate. In order to block moisture from the outside and increase resistance to hydrofluoric acid generated by hydrolysis of the electrolytic solution and moisture, the density of the second adhesive layer 4 should be high, and more preferable density. lower limit is at 0.923 g / cm ³ or more, and particularly preferably 0.925 g / cm ³ or more. The upper limit of the density of the second adhesive layer 4 is not particularly limited as long as the flexibility of the polyethylene resin is not impaired. Usually, the upper limit of the density is 0.950 g / cm ³ or less, and In consideration of adhesiveness, acid resistance to hydrogen fluoride, and resistance to whitening in pressing or overhanging, the upper limit of the density is preferably 0.945 g / cm ³ or less.
Means for bringing the density of the second adhesive layer 4 within the above range is not limited, but examples include a method of appropriately selecting a polyethylene resin to be used. In particular, optimization of the polyethylene resin used for acid modification, modification rate In addition to optimization, as described above, it is possible to use a polyethylene resin that is not acid-modified, a resin other than polyethylene resin, and the like to optimize the blending ratio.

  Further, the tensile modulus of elasticity of the second adhesive layer 4 is preferably 100 MPa or more because it tends to cause material destruction when an external force such as deformation is applied if too much flexibility is applied. It is preferably 1000 MPa or less because it tends to become brittle and easily peels at the interface with the barrier layer. The tensile elastic modulus of the second adhesive layer 4 is more preferably 130 MPa to 800 MPa, and particularly preferably 180 MPa to 600 MPa.

  The values of MFR, density, and tensile modulus described above indicate the characteristics of the material constituting the second adhesive layer 4, and when a plurality of polyethylene resins are used in combination as the polyethylene resin, a resin other than the polyethylene resin is used. In the case of containing, it means a value as a resin composition.

  The thickness of the second adhesive layer 4 is preferably 3 μm or more and 50 μm or less, more preferably 10 μm or more and 40 μm or less, and particularly preferably 12 μm or more and 35 μm or less. If the thickness of the second adhesive layer 4 is thinner than the above range, it may not be possible to obtain sufficient adhesive strength for the adhesion between the barrier layer 3 and the sealant layer 5. If thicker than the above range, the sealant layer 5 The thickness of the electrode must be reduced, and the electrolyte solution resistance may be inferior.

[Method for producing laminated film for battery exterior]
Hereinafter, the method for producing the laminate film for battery exterior of the present invention will be described by exemplifying the case where the sealant layer has the single layer structure of the above-mentioned (I) layer. In addition, what is necessary is just to form into a film by the coextrusion inflation molding method below, when making a sealant layer into the laminated structure of (I) layer and another layer.

The method for producing the laminate film for battery exterior of the present invention is not particularly limited, but at least the sealant layer is formed by an inflation molding method, and then the barrier layer and the barrier layer through the second adhesive layer by a thermal lamination method. It is preferable to bond them together.
In addition, a laminated film of the second adhesive layer and the sealant layer is formed in advance by the coextrusion inflation molding method (multilayer inflation molding method), and then the metal foil / second adhesive layer / sealant layer is formed by the thermal lamination method. It is good also as a laminated film. Further, the second adhesive layer and the sealant layer may be separately formed in advance, and these may be bonded together at the time of thermal lamination to form a laminated film of metal foil / second adhesive layer / sealant layer. Moreover, you may laminate by extruding a 2nd contact bonding layer between the sealant layer previously formed by the inflation molding, and the barrier layer bonded together with the base material layer.
In any case, since the (I) layer of the sealant layer in the present invention is excellent not only in polyethylene but also in adhesion to polypropylene, the crystallinity of the sealant layer and the second adhesive layer is increased during thermal lamination. The crystal lamellae of the sealant layer creates electrolyte resistance, and the crystal lamellae of the acid-modified polyethylene resin of the second adhesive layer can easily enter the metal foil surface of the barrier layer, resulting in high adhesive strength, heat resistance, and electrolysis resistance. Liquidity is obtained.

  In addition, the metal foil of the barrier layer used for thermal lamination should be used as a laminated film in which a base material layer is bonded in advance through a first adhesive layer by a dry lamination method or the like. This is preferable because the side is cooled more slowly, crystallization proceeds, and a laminate film for battery exterior having excellent heat resistance and electrolytic solution resistance can be obtained.

  Thereafter, a film of a sealant layer and a second adhesive layer are respectively formed by an inflation molding method, and this is bonded to a barrier layer, preferably a base material layer bonded to the first adhesive layer, by thermal lamination. The method for producing the laminate film for battery exterior of the present invention will be described.

<Inflation molding>
Inflation molding is a method in which air or the like is placed in a melting tube made of a film forming material extruded from an annular die, inflated larger than the diameter of the annular die, and continuously taken and filmed while being cooled and solidified by air cooling or water cooling. Extrusion method.

  In the inflation molding method, the molten resin extruded from the extruder is formed into a tube shape, and the molten resin flows through an annular flow path using an inflation die. This flow path is between the outer die and the inner mandrel. Immediately after the molten resin film exits the annular die, air pressure is applied inside the tube to expand it. The expanded tube is configured to be tightened with a nip roll to maintain air pressure. The expanded tube (bubble) is cooled with air from the cooling ring above the die exit.

  Since the bubble grows in the extrusion direction (MD direction) and the circumferential direction (TD direction), the film speed at the nip roll must be much faster than the tube speed at the die exit. The film is stretched in the MD direction and expanded in the TD direction. The stretch ratio is expressed as the ratio between the final film speed and the initial speed, and the blow-up ratio is expressed as the ratio between the final tube diameter and the initial diameter (annular die diameter). The size of the blow-up ratio is from 1: 1 to 10: 1. A range is preferred, with a range of 1.3: 1 to 5: 1 being particularly preferred.

In general, polypropylene is often used as the resin for the battery exterior film from the viewpoint of heat resistance, and in order to emphasize low cost, it is manufactured by an extrusion lamination method, a sand lamination method, or a casting method. Often filmed polypropylene is used. However, since all of these films are formed by cooling the molten resin extruded from a T-shaped mold (strip-shaped resin discharge port), physical properties such as tensile strength, elongation, and tensile modulus in the MD and TD directions are obtained. Differences are likely to occur. Therefore, when used as a battery exterior film, at the time of press working or overhanging, wrinkles at the time of working tend to occur due to the difference in mechanical properties depending on the direction.
Further, as described above, since the highly elastic film of the base material layer is usually stretch-molded with a T-die, the difference in the MD / TD direction is likely to occur.

  For this reason, in the present invention, the sealant layer and further the second adhesive layer are less likely to cause a difference in physical properties in the MD / TD direction by inflation molding, and balance with the physical properties of the base material layer. In view of the above, it is preferable that the laminated film for battery exterior is formed by adjusting the blow-up ratio within the above range so as to eliminate anisotropy.

  As described above, the film formed by the inflation molding method is unlikely to have a difference in mechanical properties between the extrusion direction (MD direction) and the circumferential direction (TD direction) perpendicular to the extrusion direction, and is subjected to press processing and overhang processing. The laminated film has an advantage that wrinkles during processing are less likely to occur because there is little difference in mechanical properties depending on the direction.

  In addition, the resin raw material suitable for the inflation molding method requires characteristics such as a low MFR, a high molecular weight, a high melt tension, and a low processing temperature during film formation. The properties are different from those of resins used in extrusion laminating or sandwich laminating methods that are molded at high temperatures and require high MFR, high flow resin properties. For this reason, in the present invention, the low MFR resin as described above is preferably used as the (I) layer resin and the acid-modified polyethylene resin of the second adhesive layer, but these resins have low MFR properties. Due to the high melt tension, there is also an advantage that a high sealing strength can be easily obtained.

  In the present invention, in order to impart various properties such as mechanical properties, sealing properties, heat resistance, moldability, etc. as a battery exterior film while taking advantage of the low anisotropy of the film by the inflation molding method, Paying attention to the resin characteristics used in the method, by constructing the sealant layer having the specific resin and specific physical properties described above, the aluminum foil without the chromium conversion treatment is applied to the aluminum foil as the barrier layer. It is possible to obtain a laminate film for battery exterior that has excellent adhesiveness, can prevent moisture intrusion, has excellent resistance to electrolytic solution, and has high sealing strength.

<Thermal lamination method>
In the present invention, a sealant layer (film for forming a sealant layer) formed by an inflation method, preferably, a laminated film of a sealant layer and a second adhesive layer is thermocompression bonded by a thermal lamination method to adhere to the barrier layer. This is important for improving the resistance to electrolytic solution.

  The thermal lamination method uses two or more rolls, sandwiches two or more films between the rolls, moves the film while rotating at least one roll, and heats the film while heating at least one roll. Is a laminating method in which the material is heated and bonded. In this method, the line speed is slower than in the dry lamination and extrusion lamination methods, but since the cooling process is not rapid, it is easy to create processing conditions that promote crystallization of the resin.

In the present invention, a compound containing the aforementioned component (A) and component (B), preferably further component (C) is used for the sealant layer, and the sealant layer and the second adhesive layer are melted by a thermal lamination method. By adopting the method of thermocompression bonding, the sealant layer and the second adhesive layer are crystallized, and further, the crystallized lamellae with the developed sealant layer are transformed into an electrolyte solution by accelerating crystallization by slowly cooling in the cooling process. In addition to producing a barrier property against the above, the polymer is entangled with the second adhesive layer made of the same kind of polymer component and has excellent adhesiveness, and also has the effect of improving the electrolytic solution resistance and heat resistance.
In addition, the crystal lamella developed in the second adhesive layer produces strong adhesion with the metal foil as the second adhesive layer and the barrier layer. As a result, the adhesive strength is increased and the crystal lamella particularly forms a boehmite film. This has the effect of entering into the pores of the boehmite film of the aluminum foil and realizing even higher adhesive strength and electrolyte resistance.

FIG. 2 shows a laminated film 14 of a second adhesive layer and a sealant layer by a thermal lamination method, and a base material layer / barrier layer laminated film 12 in which the base material layer is laminated and integrated with the barrier layer in advance by the first adhesive layer. The second adhesive layer / sealant layer laminated film 14 and the base material layer / barrier layer fed from the wound body 13 of the second adhesive layer / sealant layer laminated film The base material layer / barrier layer laminated film 12 fed from the laminated film wound body 11 and the heat-resistant resin film 16 fed from the heat-resistant film wound body 15 are heated and pressurized between the heating rolls 17A and 17B. As a result, the second adhesive layer side 14A of the second adhesive layer / sealant layer laminated film 14 and the barrier layer side 12A of the base material layer / barrier layer laminated film 12 are thermally laminated. That.
The heat-laminated laminate film 10 for battery exterior passes between the feed rolls 18A and 18B and is taken up by the take-up roll 20.
On the other hand, the heat-resistant resin film 16 is peeled off from the battery exterior laminate film 10 and wound up on a winding roll 19.

  In such a thermal lamination method, the heating temperature between the heating rolls 17A and 17B can be arbitrarily set at a temperature that reaches the temperature at which the second adhesive layer and the sealant layer melt, but the heating roll on the sealant layer side The temperature of 17A is 20 ° C. or more, preferably 25 to 100 ° C. higher than the melting point of the sealant layer ((I) layer). The lamellar crystal of the layer is easy to grow, which is preferable in that the adhesive strength between the sealant layer and the second adhesive layer and the adhesive strength between the second adhesive layer and the barrier layer are improved. If the temperature of the heating roll 17A is lower than the lower limit, the sealant layer and the second adhesive layer tend not to melt and the adhesive strength tends to be insufficient. If the temperature is higher than the upper limit, the resin of the sealant layer and the second adhesive layer Tends to flow and the adhesive strength between the layers tends to decrease. The melting point of the sealant layer is usually about 120 to 168 ° C.

  In addition, the heating temperature in the thermal lamination is such that the temperature on the second adhesive layer side, that is, the temperature on the heating roll 17A and the temperature on the barrier layer side, that is, the temperature on the heating roll 17B is different. This is preferable because the crystal orientation of the acid-modified polyethylene resin of the adhesive layer 2 is further enhanced, crystal growth in the thickness direction is promoted, and the barrier layer is more strongly bonded. In this case, the temperature on the second adhesive layer side, that is, the temperature of the heating roll 17A is 170 ° C. or higher, for example, 200 ° C. or higher and 260 ° C. or lower, including the relationship with the melting point of the sealant layer. That is, the temperature of the heating roll 17B is less than 170 ° C., for example, 120 ° C. or more and 165 ° C. or less, and it is desirable to give a temperature difference of 10 ° C. or more, preferably 20 ° C. or more and 70 ° C. or less. If the temperature of the heating rolls 17A and 17B is too low, sufficient adhesion cannot be performed. However, if the temperature is too high, the resin deteriorates or melts and flows to reduce the thickness of the adhesive layer, resulting in sufficient adhesion. There is a tendency to disappear. Moreover, if the temperature difference between the two is too small, the effect of promoting crystal growth by providing the temperature difference cannot be sufficiently obtained, and excessively increasing this temperature difference is the setting temperature of each heating roll. It is difficult to meet the conditions.

In addition, when thermal lamination is performed at such a high temperature, the resin of the sealant layer may be welded to the heating roll. The purpose of preventing this welding is to promote the growth of the crystal lamella of the second adhesive layer on the surface of the barrier layer and the growth of the crystal lamella to the second adhesive layer of the sealant layer, thereby further strengthening the adhesion between the layers. For the purpose, it is preferable to overlap the heat resistant resin film 16 on the further outer side (non-bonded surface) of the sealant layer as shown in FIG. 2 and to peel off the heat resistant resin film 16 after thermal lamination.
At this time, a heat resistant resin film having a surface roughness Ra of 0.1 μm or more and 1 μm or less, preferably 0.25 μm or more and 0.75 μm or less by matting or the like in advance on at least the side of the heat resistant resin film that comes into contact with the sealant layer. When it is used, the unevenness of the heat-resistant film is thermally transferred to the sealant layer at the time of thermal lamination, and appropriate unevenness is imparted to the surface of the sealant layer, so that the slipperiness with the mold necessary for embossing can be obtained.

  The heat-resistant resin film 16 has excellent heat resistance, is not welded to the heating roll 17A during thermal lamination, and is not weldable to the sealant layer. For example, the melting point is higher than the temperature of the heating roll 17A, and the sealant layer A resin film made of a resin other than a polyethylene resin, which has a melting point of 20 ° C. or higher than the melting point and does not thermally bond with the polyethylene resin of the sealant layer is preferable. Particularly preferred is a thermoplastic resin film similar to the above-mentioned base material layer, which has a melting point 20 ° C. or more higher than the melting point of the sealant layer, for example, a melting point of 150 ° C. or more, preferably 200 to 350 ° C. Can be used. Specifically, a biaxially stretched PA film, a biaxially stretched PET film, a biaxially stretched PP film, a uniaxially stretched PP film, an unstretched PP film, and the like are preferable. The thickness of the heat resistant resin film 16 is usually 25 μm or more and 125 μm or less. If the heat-resistant resin film 16 is too thin, the crystal lamella growth promoting effect due to the provision of the heat-resistant resin film 16 may not be sufficiently obtained, and if it is too thick, the heating efficiency during thermal lamination tends to deteriorate. is there.

[Battery exterior materials]
The laminated film for battery exterior of the present invention can be processed into a battery exterior material according to a conventional method.
The battery exterior material forms an exterior body that wraps the battery body, and there are a pouch type and an emboss type depending on the type.

FIG. 3 shows an embodiment of an embossed type exterior material. The first exterior material 31 is formed with a recess that serves as a housing portion 31b of the battery body 30, and a flange (flange) 31a is formed at the periphery of the opening. Has been. The second exterior material 32 is a lid material that covers the opening of the first exterior material 31. As for the 1st exterior material 31, the inner wall side of the accommodating part 31b becomes a sealant layer, and as for the 2nd exterior material 32, the contact surface side to the 1st exterior material 31 becomes a sealant layer.
A film made of polypropylene or the like is wound as a tab seal layer (not shown) on the electrode tab where the electrode tabs 30A and 30B are in contact with the flange portion (flange) 31a and the second exterior member 32.
The battery is assembled by covering the second exterior member 32 with the first exterior member 31 with the electrode tabs 30A and 30B pulled out, and heat-sealing the periphery.

In addition to the embossed type exterior material having the recesses formed on one side in this way, there is a type in which the recesses are formed on both exterior materials. In addition, there is a type in which a lid piece portion corresponding to the second exterior material extends from the flange on one side of the first exterior material.
On the other hand, the pouch type has a bag shape such as a three-side seal type, a four-side seal type, and a pillow type.

  The laminate film for battery exterior of the present invention can be used as various battery exterior materials including embossed type, pouch type and the like.

[battery]
The battery of the present invention is one in which a battery body is enclosed in an exterior material made of the laminate film for battery exterior of the present invention, and in various batteries such as lithium batteries and fuel cells, it is light, thin, small, and low in cost. In addition, long-term durability and reliability can be improved.

  EXAMPLES Hereinafter, the present invention will be described more specifically with reference to examples. However, the present invention is not limited to the following examples unless it exceeds the gist.

In the following examples and comparative examples, the materials used for forming the sealant layer and the second adhesive layer are as shown in Table 1 below.
The acid-modified LLPE-1 used for the second adhesive layer has butene-1 as a side chain and mainly contains LLPE made of an ethylene-propylene copolymer having an ethylene content of 70% by weight. In this case, acid-modified high-density polyethylene is blended.
Metallocene PE-1, -2, -3 in Table-1 corresponds to the metallocene polyethylene of component (A).
Component (B): rubber-dispersed polypropylene elastomer is a type in which an ethylene-propylene copolymer rubber having a dispersed particle size of 0.2 μm or less has a continuous phase structure in a homopolypropylene matrix (hereinafter referred to as “PP-E”). Abbreviated as “)”. The rubber content of PP-E is 50% by weight.
As the polyethylene-based elastomer (hereinafter abbreviated as “PE-E”), component (C): ethylene-1-octene block copolymer was used.

[Examples 1-9, Comparative Examples 1-7]
A laminate film for battery exterior was produced by the following method.
As the barrier layer, a JIS 8079-O material (soft aluminum foil containing 1.0% by weight of iron) having a thickness of 40 μm subjected to boehmite treatment was used.
The boehmite treatment was performed by immersing the aluminum foil in 95 ° C boehmite treated water in which triethanolamine was added to deionized water at a concentration of 0.4% by weight for 1 minute, and the boehmite having a thickness of 0.25 µm. A needle-like crystal film was formed.

Next, as a base material layer, a biaxially stretched polyamide film (tensile elastic modulus 2500 MPa, density 1.148 g / cm ³ ) having a thickness of 25 μm and a surface roughness Ra of 0.03 μm and subjected to corona treatment is used. Laminate one side of the aluminum foil and the corona-treated side of the biaxially stretched polyamide film via an adhesive layer for dry lamination (first adhesive layer) of .5μm aromatic polyester and polyisocyanate. It was.

  Using the acid-modified LLPE-1 for the second adhesive layer, the composition of the component composition described in Table-2 for the sealant layer, and using a co-extrusion inflation molding machine extruded from an extruder with a diameter (barrel inner diameter) of 75 mm, Extruded from a spiral annular die having an annular die diameter of 300 mm and a die gap of 3 mm, taken up at a tube diameter of 560 mm, a blow-up ratio of 1.87, a take-up speed of 15 m / min, and a second adhesive layer thickness of 12 μm, a sealant layer The film was formed as a two-layer film while adjusting the extrusion amount of the extruder so that the thickness of the film became 38 μm.

  Using the two-layer film of the second adhesive layer and the sealant layer obtained by the above-mentioned method, as shown in FIG. 2, the biaxially stretched polyamide film / The laminated film was laminated with an aluminum foil by a thermal lamination method. In this thermal lamination, the temperature of the heating roll 17A on the sealant layer laminated film side was 200 ° C., and the temperature of the heating roll 17B on the biaxially oriented nylon film / aluminum foil laminated film side was 180 ° C. As the heat resistant resin film 16, a 75 μm thick PET film (melting point: 260 ° C.) was used. The surface of the PET film in contact with the sealant layer has irregularities with a surface roughness Ra of 0.06 μm.

The laminate film for battery exterior thus obtained was evaluated for laminate strength, seal strength, electrolytic solution resistance, and adhesive strength with the tab seal layer (tab seal strength) by the following methods. It was shown to.
In addition, the unevenness | corrugation of surface roughness Ra0.06micrometer was formed in the sealant layer surface of the obtained laminate film for battery exteriors by the surface unevenness | corrugation of PET film used as a heat resistant resin film.

<Lamination strength>
For the laminate strength between the aluminum foil and the second adhesive layer, a sample cut into a strip shape with a width of 15 mm was used, and the 180 ° peel strength at the interface between the aluminum foil and the second adhesive layer was measured using a Tensilon tensile test. It measured on the conditions of the tension speed of 50 mm / min using the machine, and this value was made into laminate strength.

<Seal strength>
The sealant layers of the two laminate films for battery exterior that were cut in advance to 65 mm × 65 mm were used at 240 ° C. over a seal width of 10 mm and a length of 65 mm using a heat sealer “OPL-200-10” with one-side heater manufactured by Fuji Impulse. Then, heat sealing was performed under conditions of a sealing pressure of 0.45 MPa and a heat sealing time of 5 seconds, and the mixture was left standing at 23 ° C. for 24 hours or more, and then the seal portion was cut into a strip having a width of 15 mm to obtain a sample for measuring the seal strength.
The seal strength was measured at a pulling speed of 300 mm / min using a Tensilon tensile tester so that the sealant layers were peeled off from each other.

<Electrolytic solution resistance (laminate strength and seal strength after immersion in electrolytic solution)>
Using ethylene carbonate: diethyl carbonate: dimethyl carbonate = 1: 1: 1 (volume ratio) as a mixed solvent, 1 mol of lithium hexafluorophosphate was dissolved in this mixed solvent, and 1 mol / L of lithium hexafluorophosphate was dissolved. A solution electrolyte was prepared.
This electrolytic solution is put into a blow bottle made of PFA (perfluoroalkoxy fluororesin), and the above-mentioned seal strength measurement sample and unsealed laminate strength measurement sample are put in the electrolytic solution, and the lid is closed. It was left in a constant temperature water bath at 80 ° C. for 50 hours. Thereafter, the sample was taken out, washed with water, and allowed to stand at 23 ° C. for 24 hours or longer. Thereafter, the laminate strength and the seal strength were measured in the same manner as described above.

<Tab seal strength (tab adhesion)>
A random PP film (Novatech EG6D 100 μm (thickness) film made by Nippon Polypro Co., Ltd.) cut into 65 mm × 65 mm as a tab seal film, and two sealant layers of a battery exterior laminate film previously cut into 65 mm × 65 mm The random PP film cut into 65 mm × 65 mm is put between the two, and a heat sealer “OPL-200-10” with a heater on one side manufactured by Fuji Impulse Co., Ltd. is used, and the seal pressure is 240 ° C. over a seal width of 10 mm and a length of 65 mm. Heat sealing was performed under the conditions of 0.45 MPa and a heat sealing time of 5 seconds. Then, after standing for 24 hours or more at 23 ° C., the strip was cut into three strips with a width of 15 mm, and the sealant layers of the above sample for measuring the seal strength were peeled off, and using a Tensilon tensile tester, the tensile speed was 300 mm. The adhesive strength with the tab seal film was measured at / min and evaluated according to the following criteria.
○: Adhesive strength 15 N / 10 mm or more Δ: Adhesive strength less than 15 N / 10 mm 10 N / 10 mm or more ×: Adhesive strength less than 10 N / 10 mm

<Heat resistance>
Based on the melting point of the sealant layer, the following criteria were used for evaluation.
○: The melting point of the sealant layer is 140 ° C. or more. X: The melting point of the sealant layer is less than 140 ° C. When the sealant layer is composed of only one component, the melting point of the component is the melting point of the sealant layer. When the sealant layer is composed of two or more components, the melting point of the component having the highest melting point among the constituent components is defined as the melting point of the sealant layer. That is, in this case, since the constituent component of the sealant layer is an incompatible material, the melting point of the component having the highest melting point can be set as the melting point of the sealant layer.

Table 2 shows the following.
Since the laminate films for battery exteriors of Examples 1 to 9 have a sealant layer formed mainly of a metallocene polyethylene having a density specified in the present invention and a rubber-dispersed olefin elastomer, sealing properties, laminate strength, Excellent in heat resistance, electrolytic solution resistance, and adhesion to the tab seal layer.

On the other hand, in Comparative Examples 1 to 3 in which the sealant layer is made of polyethylene apparently in the density range specified in the present invention by blending with low-density polyethylene or high-density polyethylene, sealability, laminate strength, Even if it is excellent in electrolyte properties, it is inferior in heat resistance and adhesiveness with polypropylene as a tab seal.
Further, Comparative Example 4 using metallocene linear low density polyethylene (metallocene LLPE), Comparative Example 5 using high density polyethylene (HDPE), Comparative Example 6 using linear low density polyethylene (LLPE), Metallocene system Comparative Example 7 using only polyethylene (metallocene PE-2) is inferior in heat resistance and adhesiveness with polypropylene as a tab seal.

In Table 2, “Comprehensive evaluation” was determined based on the following criteria as a battery exterior laminate film.
○: Laminate strength, seal strength, heat resistance, electrolytic solution resistance, and tab seal strength are excellent.
Δ: Laminate strength, seal strength, heat resistance, electrolytic solution resistance, and tab seal strength are at usable levels.
X: Laminate strength, seal strength, heat resistance, electrolytic solution resistance, and tab seal strength are insufficient.

DESCRIPTION OF SYMBOLS 1 Base material layer 2 1st contact bonding layer 3 Barrier layer 4 2nd contact bonding layer 5 Sealant layer 10 Laminate film for battery exterior 12 Base material layer / barrier layer laminated film 14 2nd adhesion layer / sealant layer laminated film 16 Heat resistance Resin film 17A, 17B Heating roll 30 Battery body 31 First exterior material 32 Second exterior material

Claims (5)

A battery exterior laminate film in which at least a base material layer, a first adhesive layer, a barrier layer, a second adhesive layer, and a sealant layer are laminated in this order, and the sealant layer includes the following component (A) and A laminate film for battery exterior, comprising at least one (I) layer formed of a blend containing the following component (B).
Component (A): Density was prepared using a metallocene catalyst 0.930 g / cm ³ or more 0.950 g / cm ³ or less polyethylene component (B): polypropylene elastomer rubber in a polypropylene matrix is dispersed   2. The laminate film for battery exterior according to claim 1, wherein the compound constituting the (I) layer further contains a component (C): an ethylene-1-octene block copolymer.   The composition constituting the layer (I) comprises 20% to 80% by weight of the component (A), 5% to 55% by weight of the component (B), and 5% of the component (C). The laminate film for battery exterior according to claim 2, wherein the laminate film is contained in an amount of from 55% to 55% by weight.   4. The laminated film for battery exterior according to claim 1, wherein the barrier layer is made of an aluminum foil in which a boehmite film is formed on at least the surface in contact with the electrolyte solution.   A battery comprising the laminate film for battery exterior according to any one of claims 1 to 4.

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