JP7207444B2 - Exterior material for power storage device - Google Patents

Description

TECHNICAL FIELD The present invention relates to an exterior material for a power storage device.

As power storage devices, for example, secondary batteries such as lithium-ion batteries, nickel-hydrogen batteries, and lead-acid batteries, and electrochemical capacitors such as electric double-layer capacitors are known. There is a demand for further miniaturization of power storage devices due to the miniaturization of mobile devices, the limitation of installation space, and the like, and lithium ion batteries with high energy density are attracting attention. Conventionally, metal cans have been used as exterior materials for lithium-ion batteries. A film configured like a sealant layer) has come to be used.

In a lithium ion battery using the multilayer film as an outer packaging material, a configuration is adopted in which the battery contents are covered with an outer packaging material containing an aluminum foil layer as a metal foil layer in order to prevent moisture from entering the battery. A lithium ion battery having such a configuration is called an aluminum laminate type lithium ion battery. Lithium-ion batteries contain a positive electrode, a negative electrode, a separator, and a lithium salt as an electrolyte in an aprotic solvent with penetrating power such as propylene carbonate, ethylene carbonate, dimethyl carbonate, diethyl carbonate, and ethylmethyl carbonate. Included is an electrolyte layer consisting of a dissolved electrolyte or a polymer gel impregnated with the electrolyte.

For aluminum laminate type lithium ion batteries, for example, a recess is formed in a part of the exterior material by cold molding, the contents of the battery are accommodated in the recess, and the remaining part of the exterior material is folded back to heat the edge part. An embossed type lithium ion battery sealed with a seal is known. The exterior material that constitutes such a lithium-ion battery is required to exhibit stable sealing performance by heat sealing, and to prevent the deterioration of the lamination strength between the aluminum foil layer and the sealant layer due to the electrolytic solution in the battery contents. ing.

In addition, along with the miniaturization of power storage devices, the thickness of the base material layer, metal foil layer, and sealant layer of the exterior material for power storage devices is progressing. is a problem.

Insulation degradation can be caused by various phenomena. For example, contact between the tab lead and the metal foil layer due to the influence of heat such as heat sealing, cracks in the sealant layer due to molding, bending, etc., and fusion of parts that should not be fused during heat sealing ( hereinafter referred to as "over-adherence"), and breakage of the sealant layer due to degassing heat sealing.

Therefore, for example, in Patent Document 1, by providing a heat-sealing layer (sealant layer) containing an adhesive polymethylpentene layer, the barrier layer and the tab of the outer package are stably prevented from shorting due to the heat and pressure of the heat-sealing. There have been proposed sheathing materials that can be sealed by

JP-A-2002-245983

In the conventional exterior material as described in Patent Literature 1, measures are taken against deterioration in insulation due to contact between the tab lead and the metal foil layer. However, no study has been made on the breakage of the sealant layer due to excessive adhesion and degassing heat sealing, which are considered to be the most important countermeasures for improving insulation according to the verifications made so far by the present inventors.

The present inventors presume that the deterioration of insulation due to over-wearing is caused by the formation of cracks when stress is applied because the over-wearing portion is in a non-uniform crystal state. . In addition, in the degassing heat seal, since heat sealing is performed while biting the above-mentioned electrolytic solution, it is presumed that the electrolytic solution foams and the sealant layer is destroyed. It is conceivable that the electrolytic solution enters from the cracks generated by these or the broken sealant layer portion and comes into contact with the metal layer, thereby degrading the insulation.

Furthermore, the deterioration of insulation caused by the formation of cracks due to excessive adhesion during heat sealing and the destruction of the sealant layer due to degassing heat sealing are easily affected by thinning of the sealant layer. In the future, it will be necessary to take measures in particular to improve sexuality.

The present invention has been made in view of the above-mentioned problems of the prior art, and an electric storage battery that can sufficiently maintain insulation after heat sealing, molding, and degassing heat sealing even when the sealant layer is thinned. An object of the present invention is to provide an exterior material for a device.

In order to achieve the above objects, the present invention provides an exterior material for a power storage device, comprising at least a base material layer, a metal foil layer provided with a corrosion prevention treatment layer on one or both surfaces, and a sealant layer in this order. According to another aspect of the present invention, there is provided an exterior material for a power storage device, wherein the sealant layer contains an ultra-high molecular weight polyolefin having a weight average molecular weight of 2.0×10 ⁵ to 1.0×10 ⁶ .

According to the exterior material for a power storage device having the above structure, even when the sealant layer is thinned, it is possible to sufficiently maintain the insulating properties after the degassing heat sealing. Further, according to the power storage device exterior material, even if the sealant layer is deformed due to heat during sealing or stress during molding, it is possible to sufficiently maintain insulation. The present inventors presume that the reason why the exterior material for a power storage device has such effects is as follows. The sealant layer of the exterior material for power storage devices undergoes deformation accompanied by volumetric changes such as electrolyte swelling, crystallization, and stretching many times in the power storage device manufacturing process such as heat sealing, degassing heat sealing, and molding. prone to defects. In particular, due to the thinning of the sealant layer, in the case of degassing heat sealing, in which heat sealing is performed while the electrolyte is trapped, the deformation of the sealant layer, which is thought to be due to the volatilization (foaming) of the electrolyte, increases, and the insulation performance deteriorates. easy to decline. A possible reason for the deterioration of the insulation due to the deformation is, for example, that the vicinity of the metal foil layer is likely to be exposed due to foaming, and the electrolyte comes into contact with the exposed portion. In addition, even top seals that heat-seal a plurality of materials such as tab sealants and metal tabs at once are likely to suffer deterioration in insulating properties due to cracks. The causes of cracks in the top seal are, for example, when the sealant layer has high fluidity in heat sealing, the film thickness tends to be non-uniform, and crystallization tends to become non-uniform during slow cooling. As a result, it is thought that stress concentrates on the portion where the density has decreased and cracks occur. In addition, cracks may be formed in the sealant layer due to excessive deposition (oversealed portion) that occurs during heat sealing, and the electrolytic solution may penetrate into the cracks, resulting in deterioration of insulation. Over-adhesion is a phenomenon in which portions of the sealant layer that should not be sealed are fused due to heat during heat-sealing. When excessive adhesion occurs in the sealant layer, the degree of crystallinity changes due to slow cooling after heat sealing, resulting in low density of the excessively adhered portion. It becomes easy to cause deterioration. Furthermore, fine cracks are likely to occur in the sealant layer due to stress during cold molding, and the electrolytic solution is likely to permeate the cracks, resulting in reduced insulation after molding. On the other hand, the ultra-high molecular weight polyolefin has a high weight average molecular weight of 2.0×10 ⁵ or more, and has high melt tension, solvent resistance, and dielectric breakdown strength. According to the above exterior material for a power storage device containing high-molecular-weight polyolefin, swelling of the sealant layer due to electrolyte solution, and defects due to flow of the sealant layer due to heat and stress during heat sealing (for example, sealant resin is damaged by heat during sealing). flow, the film thickness distribution of the sealed part becomes uneven, and as a result, the crystallization state differs during slow cooling after sealing), defects associated with excessive adhesion during heat sealing, and degassing heat. It is thought that deformation of the sealant layer due to foaming during sealing can be suppressed, and sufficient insulation can be maintained. In addition, since the ultra-high molecular weight polyolefin has a weight average molecular weight of 1.0×10 ⁶ or less, poor dispersion of the resin can be suppressed, and the sealant layer can be formed while suppressing the number of fish eyes.

In the power storage device exterior material, the content of the ultra-high molecular weight polyolefin in the sealant layer is preferably 5.0 to 50.0% by mass based on the total mass of the sealant layer.

When the content of the ultra-high molecular weight polyolefin is 5.0% by mass or more, deterioration of insulation can be further suppressed. In addition, when the content of the ultra-high molecular weight polyolefin is 50.0% by mass or less, it becomes easier to add a modifier for satisfying required properties such as electrolytic solution properties, mold whitening resistance, and degassing seal strength. It becomes easier to perform high-speed processing while maintaining film formability.

In the power storage device exterior material, the sealant layer may be composed of a plurality of layers, at least one of which may be a layer containing the ultrahigh molecular weight polyolefin.

When the sealant layer consists of multiple layers, each layer can be given a function such as an adhesive function, a deformation control function, a heat sealing function, or a swelling control function. Easy to improve overall. In addition, depending on the number and position of the layers containing ultra-high molecular weight polyolefin (hereinafter also referred to as "ultra-high molecular weight polyolefin-containing layers") in the sealant layer, the degree of deformation of the sealant layer can be easily controlled, further reducing the deterioration of insulation. can be suppressed. Specifically, for example, when the sealant layer is composed of a layer containing ultra-high molecular weight polyolefin and a layer not containing ultra-high molecular weight polyolefin, even if the layer side not containing ultra-high molecular weight polyolefin is deformed, It is considered that the layer containing the high-molecular-weight polyolefin can suppress the deformation, and can maintain the required properties and improve the insulating properties at the same time. In addition, when the ultra-high molecular weight polyolefin-containing layers are in contact with each other, it is thought that the deformation of the entire sealant layer can be suppressed and the insulation can be further improved. Therefore, it is considered that by adjusting these layer structures, the degree of deformation of the sealant layer can be easily controlled, and the deterioration of the insulation can be further suppressed.

In the power storage device exterior material, the sealant layer is composed of a plurality of layers, of which the layer closest to the metal foil layer (hereinafter also referred to as "metal foil side layer") is a layer containing the ultrahigh molecular weight polyolefin. Preferably.

When the metal foil side layer of the sealant layer is a layer containing ultra-high molecular weight polyolefin, it is possible to suppress deterioration in insulation while maintaining necessary properties, and to maintain good insulation for a longer period of time. This is because the layers other than the metal foil side of the sealant layer satisfy the required properties, while the metal foil side layer suppresses the breakage of the sealant layer due to swelling and foaming due to the electrolytic solution, and exposes the vicinity of the metal foil layer. This is considered to be because contact with the electrolytic solution can be suppressed for a long period of time.

When the metal foil side layer of the sealant layer is an ultra-high molecular weight polyolefin-containing layer, the metal foil side layer further includes an acid-modified polypropylene and an atactic structure polypropylene or an atactic structure propylene-α olefin copolymer. It can be layers. This makes it easier to suppress a decrease in lamination strength and a decrease in insulation when the electrolytic solution is involved.

The ultra-high molecular weight polyolefin preferably contains ultra-high molecular weight polypropylene, and more preferably the ultra-high molecular weight polypropylene contains ultra-high molecular weight random polypropylene. The sealant layer containing ultra-high molecular weight polyolefin can increase the cohesion of the sealant layer itself when it softens due to the effect of the entanglement of the molecular chains of the ultra-high molecular weight polyolefin. It is possible to make it easier to prevent the bag-shaped exterior material from breaking due to heat generation of the power storage device. The ultra-high-molecular-weight polyolefin is ultra-high-molecular-weight polypropylene, which has a higher melting point and higher heat resistance than ultra-high-molecular-weight polyethylene. It becomes easier to prevent the bag from breaking. In addition, by including ultra-high-molecular-weight random polypropylene in the ultra-high-molecular-weight polyolefin, in addition to making it easier to prevent bag breakage of the exterior material, in order to increase the efficiency of battery production, low heat sealing (low-temperature, short-time )can do. When random polypropylene is used as the main component of the sealant layer and ultra-high molecular weight random polypropylene is contained as the ultra-high molecular weight polyolefin, it is easy to suppress the occurrence of cracks in the exterior material due to molding, and the exterior material has whitening resistance. is easier to give. Therefore, it becomes easier to achieve both insulation and the various required properties described above.

The power storage device exterior material further includes an adhesive layer between the metal foil layer and the sealant layer, and the adhesive layer comprises an acid-modified polyolefin, a polyfunctional isocyanate compound, a glycidyl compound, and a compound having a carboxy group. , and at least one curing agent selected from the group consisting of a compound having an oxazoline group and a carbodiimide compound. According to such an exterior material for a power storage device, a decrease in lamination strength and a decrease in insulating properties in the case where the electrolytic solution is involved is further suppressed.

In the power storage device exterior material, the corrosion prevention treatment layer contains cerium oxide, 1 to 100 parts by mass of phosphoric acid or a phosphate with respect to 100 parts by mass of the cerium oxide, and a cationic polymer. may be Further, in the power storage device exterior material, the corrosion prevention treatment layer may be formed by subjecting the metal foil layer to chemical conversion treatment, or may be formed by subjecting the metal foil layer to chemical conversion treatment. and may contain a cationic polymer. According to such an exterior material for a power storage device, a decrease in lamination strength and a decrease in insulating properties in the case where the electrolytic solution is involved is further suppressed.

ADVANTAGE OF THE INVENTION According to this invention, the exterior material for electrical storage apparatuses which can maintain the insulation fully after heat-sealing, molding, and degassing heat-sealing can be provided, even when a sealant layer becomes thin. The exterior material for a power storage device of the present invention has a thin film structure, for example, a structure in which the total thickness of the inner layer side of the metal foil layer is 35 μm or less, and the insulating properties after heat sealing, molding, and degassing heat sealing are maintained. can be sufficiently maintained.

1 is a schematic cross-sectional view of an exterior material for a power storage device according to an embodiment of the present invention; FIG. 1 is a schematic cross-sectional view of an exterior material for a power storage device according to an embodiment of the present invention; FIG. 1 is a schematic cross-sectional view of an exterior material for a power storage device according to an embodiment of the present invention; FIG. It is a schematic diagram explaining the preparation method of the evaluation sample in an Example. It is a schematic diagram explaining the preparation method of the evaluation sample in an Example. It is a schematic diagram explaining the preparation method of the evaluation sample in an Example. It is a schematic diagram explaining the preparation method of the evaluation sample in an Example. It is a schematic diagram explaining the preparation method of the evaluation sample in an Example.

Preferred embodiments of the present invention will be described in detail below with reference to the drawings. In the drawings, the same or corresponding parts are denoted by the same reference numerals, and redundant explanations are omitted. Also, the dimensional ratios in the drawings are not limited to the illustrated ratios.

The exterior material for a power storage device of the present embodiment includes at least a base material layer, a metal foil layer provided with a corrosion prevention treatment layer on one or both surfaces, and a sealant layer in this order. It comprises an ultra-high molecular weight polyolefin having a weight average molecular weight of 10 ⁵ to 1.0×10 ⁶ . Further, the exterior material for a power storage device of the present embodiment may include an adhesive layer between the metal foil layer having a corrosion prevention treatment layer on one or both surfaces thereof and the sealant layer. Hereinafter, the exterior material for a power storage device of the present embodiment will be described while exemplifying several modes.

[Exterior material for power storage device]
FIG. 1 is a cross-sectional view schematically showing one embodiment of the exterior material for a power storage device of the present embodiment. As shown in FIG. 1, the exterior material (exterior material for power storage device) 10 of the present embodiment includes a base material layer 11 and an adhesive layer 12 (first adhesive layer) formed on one surface of the base material layer 11 . (sometimes referred to as adhesive layer 12), a metal foil layer 13 formed on the surface of the first adhesive layer 12 opposite to the base layer 11, and the first adhesive layer 13 of the metal foil layer 13 A corrosion prevention treatment layer 14 formed on the surface opposite to the adhesive layer 12 and an adhesive layer 17 formed on the surface of the corrosion prevention treatment layer 14 opposite to the metal foil layer 13 (second ) and a sealant layer 16 formed on the opposite side of the second adhesive layer 17 from the anti-corrosion treatment layer 14 are sequentially laminated. In the exterior material 10, the base material layer 11 is the outermost layer, and the sealant layer 16 is the innermost layer. That is, the exterior material 10 is used with the base material layer 11 facing the outside of the power storage device and the sealant layer 16 facing the inside of the power storage device. Each layer will be described below.

<Base material layer 11>
The base material layer 11 is provided for the purpose of imparting heat resistance in the sealing process during the manufacture of the electric storage device and for countermeasures against pinholes that may occur during processing and distribution, and it is preferable to use an insulating resin layer. As such a resin layer, for example, stretched or unstretched films such as polyester film, polyamide film and polypropylene film can be used as a single layer or a multilayer film obtained by laminating two or more layers. It is also possible to use a co-extruded multi-layer stretched film obtained by co-extrusion of a polyethylene terephthalate (PET) film and a nylon (Ny) film using an adhesive resin followed by stretching.

The thickness of the substrate layer 11 is preferably 6-40 μm, more preferably 10-25 μm. When the thickness of the base material layer 11 is 6 μm or more, there is a tendency that the resistance to pinholes and the insulating properties of the exterior material 10 for a power storage device can be improved. On the other hand, when the thickness of the base material layer 11 is 40 μm or less, there is a tendency that the deep drawability of the power storage device exterior material 10 can be sufficiently maintained.

The base material layer 11 may be provided by directly coating on the metal foil layer 13 described below. In this case, the first adhesive layer 12, which will be described later, is unnecessary. As a method for forming the substrate layer by coating, a method of coating a resin coating liquid such as urethane resin, acrylic resin, or polyester resin and curing by ultraviolet irradiation, high-temperature heating, aging (curing) treatment, or the like can be employed. When the resin coating liquid is a urethane resin, specifically, for example, a polyurethane resin obtained by reacting a difunctional or higher isocyanate compound on a main agent such as polyester polyol, polyether polyol, acrylic polyol, or carbonate polyol is used. be able to. The coating method is not particularly limited, and various methods such as gravure coating, reverse coating, roll coating and bar coating can be employed.

<First adhesive layer 12>
The first adhesive layer 12 is a layer that bonds the base layer 11 and the metal foil layer 13 together. Specifically, the material constituting the first adhesive layer 12 is, for example, a polyurethane obtained by reacting a difunctional or higher isocyanate compound on a main agent such as polyester polyol, polyether polyol, acrylic polyol, or carbonate polyol. Resin etc. are mentioned.

The various polyols described above can be used alone or in combination of two or more according to the functions and performances required for the exterior material.

Furthermore, for the purpose of promoting adhesion, a carbodiimide compound, an oxazoline compound, an epoxy compound, a phosphorus compound, a silane coupling agent, or the like may be added to the polyurethane resin described above.

In addition, various other additives and stabilizers may be added to the polyurethane resin described above, depending on the performance required for the adhesive.

The thickness of the first adhesive layer 12 is not particularly limited, but is preferably 1 to 10 μm, and preferably 3 to 7 μm, from the viewpoint of obtaining desired adhesive strength, conformability, workability, and the like. more preferred.

<Metal foil layer 13>
The metal foil layer 13 has a water vapor barrier property that prevents moisture from entering the power storage device. In addition, the metal foil layer 13 has extensibility for deep drawing. Various metal foils such as aluminum, stainless steel, and copper can be used as the metal foil layer 13, and aluminum foil is preferable in terms of mass (specific gravity), moisture resistance, workability, and cost.

As the aluminum foil, a soft aluminum foil that has been subjected to an annealing treatment can be preferably used because it can impart the desired ductility during molding. For this purpose, it is more preferable to use aluminum foil containing iron. The content of iron in the aluminum foil is preferably 0.1 to 9.0% by mass, more preferably 0.5 to 2.0% by mass, based on 100% by mass of the aluminum foil. When the iron content is 0.1% by mass or more, it is possible to obtain the exterior material 10 having more excellent pinhole resistance and extensibility. When the iron content is 9.0% by mass or less, it is possible to obtain the exterior material 10 that is more excellent in flexibility.

The thickness of the metal foil layer 13 is not particularly limited, but is preferably 9 to 200 μm, more preferably 15 to 100 μm, in consideration of barrier properties, pinhole resistance, and workability. .

When an aluminum foil is used for the metal foil layer 13, an untreated aluminum foil may be used as the aluminum foil, but it is preferable to use a degreased aluminum foil in terms of imparting electrolytic solution resistance.

When the aluminum foil is degreased, only one side of the aluminum foil may be degreased, or both sides may be degreased.

<Corrosion prevention treatment layer 14>
The corrosion prevention treatment layer 14 is a layer provided to prevent corrosion of the metal foil layer 13 by the electrolyte or hydrofluoric acid generated by the reaction between the electrolyte and water. The corrosion prevention treatment layer 14 is formed by, for example, degreasing treatment, hydrothermal transformation treatment, anodizing treatment, chemical conversion treatment, or a combination of these treatments.

Examples of the degreasing treatment include acid degreasing and alkaline degreasing. Examples of acid degreasing include a method using an inorganic acid such as sulfuric acid, nitric acid, hydrochloric acid, and hydrofluoric acid alone, or a mixed solution thereof. In addition, as acid degreasing, an acid degreasing agent obtained by dissolving a fluorine-containing compound such as monosodium ammonium difluoride in the inorganic acid is used. Not only is the effect obtained, but it is also possible to form passivated aluminum fluoride, which is effective in terms of resistance to hydrofluoric acid. Alkaline degreasing includes a method using sodium hydroxide or the like.

The hydrothermal modification treatment includes, for example, a boehmite treatment in which an aluminum foil is immersed in boiling water containing triethanolamine.

Examples of the anodizing treatment include alumite treatment.

Examples of the chemical conversion treatment include dipping type and coating type. Immersion-type chemical conversion treatments include, for example, chromate treatment, zirconium treatment, titanium treatment, vanadium treatment, molybdenum treatment, calcium phosphate treatment, strontium hydroxide treatment, cerium treatment, ruthenium treatment, and various chemical conversion treatments consisting of mixed phases thereof. be done. On the other hand, as coating type chemical conversion treatment, there is a method of coating the metal foil layer 13 with a coating agent having anti-corrosion performance.

Among these anti-corrosion treatments, when at least a part of the anti-corrosion treatment layer is formed by any one of hydrothermal transformation treatment, anodizing treatment, and chemical conversion treatment, it is preferable to perform the above-described degreasing treatment in advance. If a degreased metal foil such as a metal foil that has undergone an annealing process is used as the metal foil layer 13, it is not necessary to perform another degreasing treatment when forming the corrosion prevention treatment layer .

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

Among the above treatments, particularly in the hydrothermal transformation treatment and the anodizing treatment, the surface of the aluminum foil is dissolved by a treating agent to form an aluminum compound (boehmite, alumite) having excellent corrosion resistance. Therefore, since a co-continuous structure is formed from the metal foil layer 13 using aluminum foil to the corrosion prevention treatment layer 14, the above treatment is included in the definition of chemical conversion treatment. On the other hand, as will be described later, it is also possible to form the corrosion prevention treatment layer 14 only by a pure coating method, which is not included in the definition of chemical conversion treatment. As this method, for example, a rare earth element oxide sol such as cerium oxide having an average particle size of 100 nm or less is used as a material that has an aluminum corrosion prevention effect (inhibitor effect) and is also suitable from an environmental point of view. method to be used. By using this method, it is possible to impart a corrosion-preventing effect to a metal foil such as an aluminum foil even by a general coating method.

Examples of the sol of the rare earth element oxide include sol using various solvents such as water-based, alcohol-based, hydrocarbon-based, ketone-based, ester-based, and ether-based solvents. Among them, water-based sols are preferable.

In order to stabilize the dispersion of the rare earth element oxide sol, inorganic acids such as nitric acid, hydrochloric acid and phosphoric acid or salts thereof, and organic acids such as acetic acid, malic acid, ascorbic acid and lactic acid are added to stabilize the dispersion. used as a modifier. Among these dispersion stabilizers, phosphoric acid in particular is used in the exterior material 10 to (1) stabilize the dispersion of the sol and (2) improve adhesion with the metal foil layer 13 by utilizing the aluminum chelating ability of phosphoric acid. , (3) Imparting electrolyte resistance by trapping aluminum ions eluted under the influence of hydrofluoric acid (passivation formation), (4) Corrosion prevention treatment layer 14 ( oxide layer), etc. are expected.

Examples of the phosphoric acid or salts thereof include orthophosphoric acid, pyrophosphoric acid, metaphosphoric acid, and alkali metal salts and ammonium salts thereof. Among these, condensed phosphoric acids such as trimetaphosphoric acid, tetrametaphosphoric acid, hexametaphosphoric acid, and ultrametaphosphoric acid, or alkali metal salts and ammonium salts thereof are preferable for exhibiting functions in the exterior material 10 . In addition, considering the dry film-forming properties (drying ability, heat quantity) when forming the corrosion prevention treatment layer 14 made of the rare earth element oxide by various coating methods using the sol of the rare earth element oxide, A sodium salt is more preferable from the point of being excellent in dehydration-condensation property. As the phosphate, a water-soluble salt is preferred.

The compounding ratio of phosphoric acid (or its salt) to the rare earth element oxide is preferably 1 to 100 parts by weight per 100 parts by weight of the rare earth element oxide. When the compounding ratio is 1 part by mass or more with respect to 100 parts by mass of the rare earth element oxide, the rare earth element oxide sol becomes more stable and the function of the exterior material 10 becomes better. The compounding ratio is more preferably 5 parts by mass or more with respect to 100 parts by mass of the rare earth element oxide. Further, when the compounding ratio is 100 parts by mass or less with respect to 100 parts by mass of the rare earth element oxide, the function of the rare earth element oxide sol is enhanced, and the performance of preventing the erosion of the electrolytic solution is excellent. The compounding ratio is more preferably 50 parts by mass or less, and even more preferably 20 parts by mass or less with respect to 100 parts by mass of the rare earth element oxide.

Since the corrosion prevention treatment layer 14 formed of the rare earth element oxide sol is an aggregate of inorganic particles, there is a possibility that the cohesion of the layer itself will be reduced even after the drying and curing process. Therefore, in this case, the corrosion prevention treatment layer 14 is preferably compounded with the following anionic polymer or cationic polymer in order to compensate for cohesive force.

The anionic polymer includes a polymer having a carboxy group, such as poly(meth)acrylic acid (or a salt thereof) or a copolymer containing poly(meth)acrylic acid as a main component. Copolymerization components of this copolymer include alkyl (meth)acrylate monomers (alkyl groups include methyl group, ethyl group, n-propyl group, i-propyl group, n-butyl group, i-butyl group, t-butyl group, 2-ethylhexyl group, cyclohexyl group, etc.); (meth)acrylamide, N-alkyl(meth)acrylamide, N,N-dialkyl(meth)acrylamide (as the alkyl group, n-propyl group, i-propyl group, n-butyl group, i-butyl group, t-butyl group, 2-ethylhexyl group, cyclohexyl group, etc.), N-alkoxy(meth)acrylamide, N,N-dialkoxy Amide group-containing monomers such as (meth)acrylamide, (alkoxy groups include methoxy group, ethoxy group, butoxy group, isobutoxy group, etc.), N-methylol (meth)acrylamide, N-phenyl (meth)acrylamide; hydroxyl group-containing monomers such as hydroxyethyl (meth) acrylate and 2-hydroxypropyl (meth) acrylate; glycidyl group-containing monomers such as glycidyl (meth) acrylate and allyl glycidyl ether; (meth) acryloxypropyltrimethoxysilane, (meth) Silane-containing monomers such as acryloxypropyltriethoxylan; isocyanate group-containing monomers such as (meth)acryloxypropylisocyanate;

These anionic polymers serve to improve the stability of the corrosion prevention treatment layer 14 (oxide layer) obtained using the rare earth element oxide sol. This is due to the effect of protecting the hard and brittle oxide layer with the acrylic resin component and the effect of capturing ion contamination (especially sodium ions) derived from phosphate contained in the rare earth element oxide sol (cation catcher). achieved. In other words, if the corrosion prevention treatment layer 14 obtained using the rare earth element oxide sol contains alkali metal ions such as sodium or alkaline earth metal ions, corrosion can be prevented starting from the place containing the ions. The treated layer 14 is likely to deteriorate. Therefore, by fixing sodium ions and the like contained in the rare earth element oxide sol with an anionic polymer, the resistance of the corrosion prevention treatment layer 14 is improved.

The corrosion prevention treatment layer 14, which is a combination of an anionic polymer and a rare earth element oxide sol, has corrosion prevention performance equivalent to that of the corrosion prevention treatment layer 14 formed by subjecting an aluminum foil to chromate treatment. Preferably, the anionic polymer is a crosslinked structure of a polyanionic polymer that is essentially water soluble. Examples of cross-linking agents used for forming this structure include compounds having isocyanate groups, glycidyl groups, carboxy groups, and oxazoline groups.

Examples of compounds having an isocyanate group include diisocyanates such as tolylene diisocyanate, xylylene diisocyanate or hydrogenated products thereof, hexamethylene diisocyanate, 4,4′ diphenylmethane diisocyanate or hydrogenated products thereof, isophorone diisocyanate; Polyisocyanates such as an adduct obtained by reacting a class with a polyhydric alcohol such as trimethylolpropane, a biuret obtained by reacting with water, or an isocyanurate which is a trimer; or these poly Block polyisocyanates obtained by blocking isocyanates with alcohols, lactams, oximes and the like are included.

Examples of compounds having a glycidyl group include ethylene glycol, diethylene glycol, triethylene glycol, polyethylene glycol, propylene glycol, dipropylene glycol, tripropylene glycol, polypropylene glycol, 1,4-butanediol, 1,6-hexanediol, Epoxy compounds reacted with glycols such as neopentyl glycol and epichlorohydrin; Polyhydric alcohols such as glycerin, polyglycerin, trimethylolpropane, pentaerythritol, and sorbitol, and epoxy compounds reacted with epichlorohydrin; Phthalic acid, terephthalate Epoxy compounds obtained by reacting dicarboxylic acids such as acid, oxalic acid and adipic acid with epichlorohydrin, and the like.

Examples of compounds having a carboxy group include various aliphatic or aromatic dicarboxylic acids. Poly(meth)acrylic acid and alkali (earth) metal salts of poly(meth)acrylic acid may also be used.

As the compound having an oxazoline group, for example, when using a low-molecular compound having two or more oxazoline units, or a polymerizable monomer such as isopropenyloxazoline, (meth)acrylic acid, (meth)acrylic acid alkyl ester , hydroxyalkyl (meth)acrylate, and other acrylic monomers are copolymerized.

Also, an anionic polymer and a silane coupling agent are reacted, more specifically, a carboxyl group of the anionic polymer and a functional group of the silane coupling agent are selectively reacted, and the cross-linking point is a siloxane bond. good. In this case, γ-glycidoxypropyltrimethoxysilane, γ-glycidoxypropyltriethoxysilane, β-(3,4-epoxycyclohexyl)ethyltrimethoxysilane, γ-chloropropylmethoxysilane, vinyltrichlorosilane, γ -Mercaptopropyltrimethoxysilane, γ-aminopropyltriethoxysilane, N-β(aminoethyl)-γ-aminopropyltrimethoxysilane, γ-isocyanatopropyltriethoxysilane, etc. can be used. Among them, epoxysilane, aminosilane, and isocyanatesilane are preferable, especially considering reactivity with anionic polymers or copolymers thereof.

The ratio of these cross-linking agents to the anionic polymer is preferably 1 to 50 parts by mass, more preferably 10 to 20 parts by mass, per 100 parts by mass of the anionic polymer. When the ratio of the cross-linking agent is 1 part by mass or more with respect to 100 parts by mass of the anionic polymer, a cross-linked structure is easily formed. If the ratio of the cross-linking agent is 50 parts by mass or less with respect to 100 parts by mass of the anionic polymer, the pot life of the coating liquid is improved.

The method of cross-linking the anionic polymer is not limited to the above-mentioned cross-linking agent, and may be a method of forming ionic cross-links using a titanium or zirconium compound.

Examples of cationic polymers include polymers having amines, such as polyethyleneimine, ionic polymer complexes composed of polymers having polyethyleneimine and carboxylic acid, primary amine-grafted acrylic resins in which primary amines are grafted onto acrylic backbones, Cationic polymers such as polyallylamine or derivatives thereof, and aminophenol can be used. Examples of polyallylamine include homopolymers or copolymers of allylamine, allylamineamide sulfate, diallylamine, dimethylallylamine, and the like. These amines may be free amines or stabilized with acetic acid or hydrochloric acid. Maleic acid, sulfur dioxide, etc. may also be used as copolymer components. Furthermore, a type in which a primary amine is partially methoxylated to impart thermal crosslinkability can also be used, and an aminophenol can also be used. Allylamine or derivatives thereof are particularly preferred.

The cationic polymer is preferably used in combination with a cross-linking agent having a functional group capable of reacting with an amine/imine such as a carboxyl group or a glycidyl group. As a cross-linking agent used in combination with a cationic polymer, a polymer having a carboxylic acid that forms an ionic polymer complex with polyethyleneimine can also be used. and polysaccharides having a carboxy group such as carboxymethyl cellulose or its ion salt.

In this embodiment, the cationic polymer is also described as one constituent element that constitutes the corrosion prevention treatment layer 14 . The reason for this is that as a result of intensive studies using various compounds in order to provide the electrolyte resistance and hydrofluoric acid resistance required for exterior materials for power storage devices, it was found that the cationic polymer itself also has electrolyte resistance and hydrofluoric acid resistance. This is because it has been found to be a compound that can be imparted. The reason for this is presumed to be that the aluminum foil is prevented from being damaged by capturing fluorine ions with cationic groups (anion catcher).

Cationic polymers are more preferred materials in terms of improved adhesion. Moreover, since the cationic polymer is also water-soluble like the anionic polymer, it is more preferable to impart water resistance by forming a crosslinked structure. As a cross-linking agent for forming a cross-linked structure in the cationic polymer, the cross-linking agent described in the section of the anionic polymer can be used. When a rare earth element oxide sol is used as the corrosion prevention treatment layer 14, a cationic polymer may be used as the protective layer instead of the anionic polymer.

In order to form a sloped structure with the aluminum foil, the corrosion prevention treatment layer by chemical conversion treatment represented by chromate treatment uses hydrofluoric acid, hydrochloric acid, nitric acid, sulfuric acid, or a chemical conversion treatment agent containing these salts to form an aluminum foil. is treated, and then a chromium or non-chromium compound is allowed to act to form a chemical conversion treatment layer on the aluminum foil. However, since the chemical conversion treatment uses an acid as a chemical conversion treatment agent, the working environment deteriorates and the coating equipment is corroded. On the other hand, unlike the chemical conversion treatment represented by chromate treatment, the coating-type corrosion prevention treatment layer 14 does not need to form an inclined structure on the metal foil layer 13 using aluminum foil. Therefore, the properties of the coating agent are not subject to restrictions such as acidity, alkalinity, neutrality, etc., and a good working environment can be realized. In addition, the chromate treatment using a chromium compound is preferably a coating type anti-corrosion treatment layer 14 from the point of view of environmental hygiene that alternatives are being sought.

From the above contents, as examples of combination of the coating type corrosion prevention treatment described above, (1) rare earth element oxide sol only, (2) anionic polymer only, (3) cationic polymer only, (4) rare earth element Oxide sol + anionic polymer (laminated composite), (5) rare earth element oxide sol + cationic polymer (laminated composite), (6) (rare earth element oxide sol + anionic polymer: laminated composite)/ Cationic polymer (multilayered), (7) (rare earth element oxide sol + cationic polymer: laminated composite)/anionic polymer (multilayered), and the like. Among them, (1) and (4) to (7) are preferred, and (4) to (7) are particularly preferred. However, this embodiment is not limited to the above combinations. For example, as an example of selecting a corrosion prevention treatment, a cationic polymer is a very preferable material in that it has good adhesion to the modified polyolefin resin mentioned in the explanation of the second adhesive layer or sealant layer to be described later. Therefore, when the second adhesive layer or sealant layer is composed of a modified polyolefin resin, a cationic polymer is provided on the surface in contact with the second adhesive layer or sealant layer (for example, configuration (5) and Configuration such as (6)) is possible.

Moreover, the corrosion prevention treatment layer 14 is not limited to the layers described above. For example, like coating-type chromate, which is a known technique, it may be formed using a treatment agent in which phosphoric acid and a chromium compound are blended in a resin binder (such as aminophenol). By using this treatment agent, it is possible to form a layer having both corrosion prevention function and adhesion. In addition, although it is necessary to consider the stability of the coating liquid, it is possible to achieve both corrosion prevention function and adhesion by using a coating agent in which the rare earth element oxide sol and polycationic polymer or polyanionic polymer are made into a single component in advance. It can be a layer that also has

The mass per unit area of the corrosion prevention treatment layer 14 is preferably 0.005 to 0.200 g/m ² , more preferably 0.010 to 0.100 g/m ² , regardless of whether it has a multilayer structure or a single layer structure. preferable. If the mass per unit area is 0.005 g/m ² or more, the metal foil layer 13 can easily be provided with a corrosion prevention function. Moreover, even if the mass per unit area exceeds 0.200 g/m ² , the corrosion prevention function does not change much. On the other hand, when a rare earth element oxide sol is used, if the coating film is thick, curing by heat during drying becomes insufficient, which may lead to a decrease in cohesive strength. The thickness of the corrosion prevention treatment layer 14 can be converted from its specific gravity.

The corrosion prevention treatment layer 14 is, for example, cerium oxide and the cerium oxide 100 from the viewpoint of further suppressing the deterioration of the electrolytic solution lamination strength and the deterioration of the insulation after heat sealing, after molding, and after degassing heat sealing. It may contain 1 to 100 parts by mass of phosphoric acid or a phosphate and a cationic polymer, and may be formed by subjecting the metal foil layer 13 to a chemical conversion treatment. Alternatively, it may be formed by subjecting the metal foil layer 13 to a chemical conversion treatment and containing a cationic polymer.

<Second Adhesive Layer 17>
The second adhesive layer 17 is a layer that bonds the metal foil layer 13 on which the corrosion prevention treatment layer 14 is formed and the sealant layer 16 . For the second adhesive layer 17, a general adhesive for bonding the metal foil layer and the sealant layer can be used.

When the corrosion prevention treatment layer 14 has a layer containing at least one polymer selected from the group consisting of the cationic polymers and anionic polymers described above, the second adhesive layer 17 is included in the corrosion prevention treatment layer 14. It is preferable that the layer contains a compound (hereinafter also referred to as a “reactive compound”) having reactivity with the above polymer.

For example, when the corrosion prevention treatment layer 14 contains a cationic polymer, the second adhesive layer 17 contains a compound reactive with the cationic polymer. When the corrosion prevention treatment layer 14 contains an anionic polymer, the second adhesive layer 17 contains a compound reactive with the anionic polymer. Further, when the corrosion prevention treatment layer 14 contains a cationic polymer and an anionic polymer, the second adhesive layer 17 contains a compound reactive with the cationic polymer and a compound reactive with the anionic polymer. . However, the second adhesive layer 17 does not necessarily contain the above two types of compounds, and may contain a compound reactive with both the cationic polymer and the anionic polymer. Here, "having reactivity" means forming a covalent bond with a cationic polymer or an anionic polymer. Moreover, the second adhesive layer 17 may further contain an acid-modified polyolefin resin.

Examples of the compound reactive with the cationic polymer include at least one compound selected from the group consisting of polyfunctional isocyanate compounds, glycidyl compounds, compounds having a carboxy group, and compounds having an oxazoline group.

These polyfunctional isocyanate compounds, glycidyl compounds, compounds having a carboxy group, and compounds having an oxazoline group include the polyfunctional isocyanate compounds, glycidyl compounds, and carboxy groups previously exemplified as cross-linking agents for forming the cationic polymer into a cross-linked structure. and a compound having an oxazoline group. Among these, polyfunctional isocyanate compounds are preferred because they are highly reactive with cationic polymers and tend to form a crosslinked structure.

The compound reactive with the anionic polymer includes at least one compound selected from the group consisting of glycidyl compounds and compounds having an oxazoline group. Examples of the glycidyl compound and the compound having an oxazoline group include the glycidyl compound and the compound having an oxazoline group exemplified above as a cross-linking agent for forming the cationic polymer into a cross-linked structure. Among these, glycidyl compounds are preferred because of their high reactivity with the anionic polymer.

When the second adhesive layer 17 contains an acid-modified polyolefin resin, the reactive compound preferably has reactivity with the acid groups in the acid-modified polyolefin resin (that is, forms covalent bonds with the acid groups). Thereby, the adhesiveness with the corrosion prevention treatment layer 14 is further enhanced. In addition, the acid-modified polyolefin resin becomes a crosslinked structure, and the solvent resistance of the exterior material 20 is further improved.

The content of the reactive compound is preferably equivalent to 10 times the amount of the acidic groups in the acid-modified polyolefin resin. If the amount is equal to or more, the reactive compound sufficiently reacts with the acidic groups in the acid-modified polyolefin resin. On the other hand, if the amount exceeds 10 equivalents, the cross-linking reaction with the acid-modified polyolefin resin is sufficiently saturated, so unreacted substances are present, and various performances may be deteriorated. Therefore, for example, the content of the reactive compound is preferably 5 to 20 parts by mass (solid content ratio) with respect to 100 parts by mass of the acid-modified polyolefin resin.

An acid-modified polyolefin resin is obtained by introducing an acidic group into a polyolefin resin. Examples of the acidic group include a carboxy group and a sulfonic acid group, with the carboxy group being particularly preferred. As the acid-modified polyolefin resin, for example, the same as the modified polyolefin resin (a) used for the first sealant layer 16a, which will be described later, can be used.

The second adhesive layer 17 may contain various additives such as flame retardants, slip agents, antiblocking agents, antioxidants, light stabilizers and tackifiers.

The second adhesive layer 17 includes, for example, an acid-modified polyolefin, a polyfunctional isocyanate compound, and a glycidyl compound, from the viewpoint of suppressing the deterioration of the laminate strength when the electrolytic solution is involved and from the viewpoint of further suppressing the deterioration of the insulation. , and at least one curing agent selected from the group consisting of a compound having a carboxy group, a compound having an oxazoline group, and a carbodiimide compound. Examples of carbodiimide compounds include N,N'-di-o-toluylcarbodiimide, N,N'-diphenylcarbodiimide, N,N'-di-2,6-dimethylphenylcarbodiimide, N,N'-bis (2,6-diisopropylphenyl)carbodiimide, N,N'-dioctyldecylcarbodiimide, N-triyl-N'-cyclohexylcarbodiimide, N,N'-di-2,2-di-t-butylphenylcarbodiimide, N- triyl-N'-phenylcarbodiimide, N,N'-di-p-nitrophenylcarbodiimide, N,N'-di-p-aminophenylcarbodiimide, N,N'-di-p-hydroxyphenylcarbodiimide, N,N '-di-cyclohexylcarbodiimide, N,N'-di-p-toluylcarbodiimide and the like.

As the adhesive for forming the second adhesive layer 17, for example, a polyurethane adhesive obtained by blending a polyester polyol composed of a hydrogenated dimer fatty acid and a diol with a polyisocyanate can be used.

The thickness of the second adhesive layer 17 is not particularly limited, but is preferably 1 to 10 μm, more preferably 3 to 7 μm, from the viewpoint of obtaining desired adhesive strength, workability, and the like.

<Sealant layer 16>
The sealant layer 16 is a layer that imparts sealing properties to the exterior material 10 by heat sealing. The sealant layer 16 may be composed of ultra-high molecular weight polyolefin.

When the sealant layer is a single layer as in FIG. 1, the sealant layer is an ultra-high molecular weight polyolefin-containing layer containing ultra-high molecular weight polyolefin.

The weight average molecular weight of the ultra-high molecular weight polyolefin is 2.0×10 ⁵ to 1.0×10 ⁶ , preferably 3.0×10 ⁵ to 1.0×10 ⁶ . Due to the ultra-high molecular weight polyolefin having a weight average molecular weight of 2.0 × 10 ⁵ or more, swelling of the sealant layer due to electrolyte solution and defects accompanying flow of the sealant layer due to heat and stress during heat sealing (for example, during sealing) The heat causes the sealant resin to flow, making the film thickness distribution of the seal uneven, resulting in defects caused by different crystallization conditions during slow cooling after sealing) and foaming during degassing heat sealing. Deformation of the sealant layer can be suppressed, and sufficient insulation can be maintained. In addition, since the ultra-high molecular weight polyolefin has a weight average molecular weight of 1.0×10 ⁶ or less, poor dispersion of the resin can be suppressed, and the sealant layer can be formed while suppressing the number of fish eyes. The weight-average molecular weight (Mw) and the molecular weight distribution (Mw/Mn) described below of the ultrahigh-molecular-weight polyolefin are determined using a high-temperature Gael permeation chromatography (GPC) device, for example, o-dichlorobenzene or trichlorobenzene. It can be measured by passing polyolefin through a column at a temperature of 135 to 170° C., and can be obtained by conversion using a calibration curve using standard polystyrene or standard polyethylene.

The molecular weight distribution (Mw/Mn) of the ultrahigh molecular weight polyolefin is preferably 6-10, more preferably 8-10. When the molecular weight distribution (Mw/Mn) is 6 or more, the compatibility between the ultrahigh molecular weight polyolefin and other components tends to be improved. When the molecular weight distribution (Mw/Mn) is 10 or less, it becomes easier to maintain insulation.

Ultra high molecular weight polyolefins include ultra high molecular weight linear polyolefins such as polyethylene and polypropylene, and ultra high molecular weight cyclic polyolefins such as polynorbornene. Preferably, the ultra-high molecular weight polyolefin is an ultra-high molecular weight linear polyolefin. The ultra-high molecular weight linear polyolefin may be linear or branched. Moreover, the ultra-high molecular weight polyolefin may be a homopolymer, a random copolymer, or a block copolymer.

Preferably, the ultra-high molecular weight polyolefin comprises ultra-high molecular weight polypropylene. When the ultra-high molecular weight polyolefin contains ultra-high molecular weight polypropylene, it becomes easier to prevent the bag-shaped exterior material from breaking due to heat generation of the power storage device.

Examples of ultrahigh molecular weight polypropylene include propylene homopolymer (homopolypropylene), ethylene-propylene block copolymer (block polypropylene), ethylene-propylene random copolymer (random polypropylene), and α-olefins other than ethylene and propylene. and propylene copolymers (propylene-based copolymers).

Specific examples of α-olefins as monomers constituting the propylene-based copolymer include 1-butene, 1-pentene, 3-methyl-1-butene, 1-hexene, 3-methyl-1-pentene, Including 4-methyl-1-pentene and the like.

More preferably, the ultra-high molecular weight polyolefin contains ultra-high molecular weight random polypropylene. By including ultra-high-molecular-weight random polypropylene in the ultra-high-molecular-weight polyolefin, in addition to making it easier to prevent the exterior material from breaking due to heat, in order to increase the efficiency of battery production, low heat sealing (low-temperature, short-time )can do. When random polypropylene is used as the main component of the sealant layer and ultra-high molecular weight random polypropylene is contained as the ultra-high molecular weight polyolefin, it is easy to suppress the occurrence of cracks in the exterior material due to molding, and the exterior material has whitening resistance. is easier to give. Therefore, it becomes easier to achieve both insulation and the various required properties described above.

The ultra-high molecular weight polyolefin-containing layer as the sealant layer 16 may contain components other than the ultra-high molecular weight polyolefin. The ultra-high molecular weight polyolefin-containing layer as the sealant layer 16 may be composed of, for example, a base resin composition (hereinafter also referred to as "base resin composition") and ultra-high molecular weight polyolefin. Here, the base resin composition refers to a component obtained by excluding ultra-high molecular weight polyolefin from all constituent components of the sealant layer 16 . At this time, the ultra-high molecular weight polyolefin and the base resin composition are preferably combined so as to be compatible with each other in order to exhibit a greater effect of suppressing foaming of the sealant layer. For example, when the ultra-high molecular weight polyolefin is ultra-high molecular weight polypropylene, the base resin component is preferably polypropylene-based, and when the ultra-high molecular weight polyolefin is ultra-high molecular weight polyethylene, the base resin component may be polyethylene-based. preferable.

When the sealant layer 16 contains the "base resin composition", the content of the "base resin composition" is, for example, 40.0 to 97.0% by mass based on the total mass of the sealant layer 16. 50.0 to 95.0% by mass, or 70.0 to 85.0% by mass. In addition, the content of the ultra-high molecular weight polyolefin is preferably, for example, 3.0 to 60.0% by mass, and 5.0 to 50.0% by mass, based on the total mass of the sealant layer 16. is more preferable, and 10.0 to 35.0% by mass is even more preferable.

When the content of the ultra-high molecular weight polyolefin is 3.0% by mass or more, deterioration of insulation can be further suppressed. Moreover, when the content of the ultra-high molecular weight polyolefin is 60.0% by mass or less, it becomes easier to add a modifier to satisfy the required properties, and it becomes easier to perform high-speed processing while maintaining film formability.

The "base resin composition" (excluding the above ultra-high molecular weight polyolefin) is not particularly limited and includes polyolefins such as polyethylene and polypropylene. As the "base resin composition", for example, (A) 60 to 95% by mass of a propylene-ethylene random copolymer and (B) 5 to 5 to 5 of a polyolefin elastomer having a melting point of 150°C or less and containing butene-1 as a comonomer. and a resin composition containing 40% by mass (hereinafter sometimes referred to as "resin composition α"). Such a resin composition has excellent compatibility with the ultra-high molecular weight polypropylene, especially when the ultra-high molecular weight polyolefin is ultra-high molecular weight polypropylene, so various properties such as lamination strength, seal strength, molding whitening resistance, etc. is expected to improve further. That is, the sealant layer 16 may be composed of the resin composition α as a base resin composition and an ultra-high molecular weight polyolefin (preferably ultra-high molecular weight polypropylene). In this case, the content of the resin composition α may be, for example, 40.0 to 97.0% by mass, or 50.0 to 95.0% by mass, based on the total mass of the sealant layer 16. may In addition, the content of the ultra-high molecular weight polyolefin may be, for example, 3.0 to 60.0% by mass, or 5.0 to 50.0% by mass, based on the total mass of the sealant layer 16. good too.

[Resin composition α (excluding the above ultrahigh molecular weight polyolefin)]
As described above, the resin composition α comprises (A) 60 to 95% by mass of a propylene-ethylene random copolymer and (B) 5 to 40% of a polyolefin elastomer having a melting point of 150° C. or less and containing butene-1 as a comonomer. % by mass.

((A) propylene-ethylene random copolymer)
(A) Propylene-ethylene random copolymers are superior in heat-sealing properties at low temperatures compared to propylene-ethylene block copolymers and propylene homopolymers, and improve sealing properties related to electrolytic solutions. can be done.

(A) In the propylene-ethylene random copolymer, the ethylene content is preferably 0.1 to 10% by mass, more preferably 1 to 7% by mass, and 2 to 5% by mass. More preferred. When the ethylene content is 0.1% by mass or more, the effect of lowering the melting point due to copolymerization of ethylene is sufficiently obtained, and the sealing properties related to the electrolytic solution can be further improved, and impact resistance can be obtained. , there is a tendency that the seal strength and molding whitening resistance can be improved. When the ethylene content is 10% by mass or less, it is possible to prevent the melting point from dropping too much, and there is a tendency to more sufficiently suppress the occurrence of excessively sealed portions. The ethylene content can be calculated from the mixing ratio of the monomers during polymerization.

(A) The melting point of the propylene-ethylene random copolymer is preferably 120 to 145°C, more preferably 125 to 140°C. When the melting point is 120° C. or higher, there is a tendency that the generation of excessively sealed portions can be more sufficiently suppressed. When the melting point is 145° C. or less, there is a tendency that the sealing properties related to the electrolytic solution can be further improved.

(A) The weight average molecular weight of the propylene-ethylene random copolymer is preferably adjusted appropriately so that the melting point is within the above range, preferably 10,000 or more and less than 200,000, more preferably 50 ,000 or more and 150,000 or less.

(A) The propylene-ethylene random copolymer may be acid-modified, for example, an acid-modified propylene-ethylene random copolymer graft-modified with maleic anhydride. By using the acid-modified propylene-ethylene random copolymer, the adhesiveness to the tab lead can be maintained even without the tab sealant.

(A) The propylene-ethylene random copolymer can be used alone or in combination of two or more.

In the resin composition α, the content of the component (A) is 60 to 95% by mass, preferably 60 to 90% by mass, more preferably 60 to 85% by mass, based on the total solid content of the resin composition α. is more preferable. When the content of the component (A) is 60% by mass or more, the effect of using the component (A) itself can improve the sealing properties. In addition, by setting the content of component (A) to 60% by mass or more, it is possible to prevent the excessive presence of component (B), so that the decrease in heat resistance of the sealant layer 16 can be suppressed, and the excessive seal portion can be suppressed. On the other hand, by setting the content of the component (A) to 95% by mass or less, the component (B) can be contained in an amount of 5% by mass or more. You can get enough.

((B) Polyolefin-based elastomer having a melting point of 150° C. or less with butene-1 as a comonomer)
(B) A polyolefin elastomer with butene-1 as a comonomer and a melting point of 150°C or less contributes to improvement of sealing properties related to the electrolytic solution, including degassing heat seal strength, and contributes to suppressing the occurrence of molding whitening. do.

The (B) polyolefin-based elastomer may or may not be compatible with the component (A). It is preferable to include both a polyolefin elastomer and an incompatible (B-2) incompatible polyolefin elastomer. Here, when the resin constituting component (A) is a propylene-ethylene random copolymer, having compatibility with component (A) (compatible system) means propylene constituting component (A). - means dispersed in an ethylene random copolymer resin with a dispersed phase size of 1 nm or more and less than 500 nm. Having no compatibility (incompatible system) means dispersing in the propylene-ethylene random copolymer resin constituting component (A) with a dispersed phase size of 500 nm or more and less than 20 μm.

(B-1) Compatible polyolefin elastomers include, for example, propylene-butene-1 random copolymers.

(B-2) Incompatible polyolefin elastomers include, for example, ethylene-butene-1 random copolymers.

(B) The melting point of the polyolefin elastomer is required to be 150° C. or less, but from the viewpoints of suppressing over-sealed parts, suppressing molding whitening, and improving sealing properties related to the electrolyte, the melting point is 60 to 120° C. and more preferably 65 to 90°C. A melting point of 150° C. or less can improve the sealing properties related to the electrolyte, especially the degassing heat seal strength. Further, when the melting point is 60° C. or higher, it is advantageous from the viewpoint of suppressing the generation of excessively sealed portions. (B) The weight average molecular weight of the polyolefin elastomer is preferably adjusted appropriately so that the melting point is within the above range, preferably 10,000 or more and less than 200,000, more preferably 50,000 or more and 150. , 000 or less.

(B) The polyolefin-based elastomer can be used singly or in combination of two or more.

In the resin composition α, the content of the component (B) is 5 to 40% by mass, preferably 10 to 40% by mass, more preferably 15 to 40% by mass, based on the total solid content of the resin composition α. is more preferable. When the content of the component (B) is 5% by mass or more, it is possible to sufficiently obtain the effect of improving the sealing properties related to the electrolytic solution, particularly the degassing heat seal strength. On the other hand, by setting the content of the component (B) to 40% by mass or less, it is possible to suppress the deterioration of the heat resistance of the sealant layer 16 and to suppress the generation of excessively sealed portions.

When component (B) contains (B-1) a compatible polyolefin elastomer and (B-2) an incompatible polyolefin elastomer, the content ratio of both ((B-1) compatible polyolefin elastomer/( B-2) Incompatible polyolefin elastomer) preferably has a mass ratio of 0.5 to 3, more preferably 1 to 2. By setting the content ratio within the above range, it is possible to improve the molding whitening resistance and the sealing properties related to the electrolytic solution in a well-balanced manner.

(Additional component)
The resin composition α may further contain components other than the components (A) and (B) described above. As components other than components (A) and (B), other resins such as LDPE (low-density polyethylene) may be added in order to improve handling and workability. The content of the other resin components to be added is preferably 10 parts by mass or less when the total mass of the sealant layer 16 is 100 parts by mass. Examples of components other than resins include slip agents, antiblocking agents, antioxidants, light stabilizers, and flame retardants. The content of components other than these resins is preferably 5 parts by mass or less when the total mass of the sealant layer 16 is 100 parts by mass.

The presence of butene-1 in the sealant layer 16 can be confirmed by assigning it with FT-IR (Fourier transform infrared spectrophotometer). Further, the content of butene-1 was determined by using a resin composition α containing a known amount of an elastomer containing a known amount of butene-1, and measuring the transmittance or absorbance of the characteristic absorption bands of components (A) and (B). It is possible to confirm by creating a calibration curve in . Furthermore, the butene-1 content of each of (B-1) compatible polyolefin elastomer and (B-2) immiscible polyolefin elastomer was similarly imaged in the characteristic absorption band of FT-IR. It can be confirmed by mapping the absorption band caused by butene-1 by microscopic FT-IR (transmission method). In addition to FT-IR, the presence and content of butene-1 can also be confirmed by measuring the sealant layer 16 with NMR.

It should be noted that the base resin composition can be variously changed in consideration of the compatibility with the ultra-high molecular weight polyolefin. For example, when the ultra-high molecular weight polyolefin is ultra-high molecular weight polyethylene, the base resin composition may contain polyethylene instead of the component (A) in the resin composition α. In this case, the base resin composition may further contain a compatible polyolefin elastomer compatible with the polyethylene instead of the component (B-1) in the resin composition α, and (B-2 ) component may contain an incompatible polyolefin elastomer that is incompatible with the polyethylene.

Although the thickness of the sealant layer 16 is not particularly limited, it is preferably in the range of 5 to 100 μm, more preferably in the range of 20 to 80 μm. Moreover, the thickness of the sealant layer 16 may be 30 μm or less from the viewpoint of thinning. Even with such a thin film structure, the exterior material for a power storage device of the present embodiment can suppress deterioration in insulation after heat sealing, molding, and degassing heat sealing.

As described above, preferred embodiments of the exterior material for a power storage device of the present embodiment have been described in detail, but the present invention is not limited to such specific embodiments, and the present invention described within the scope of claims. Various modifications and changes are possible within the scope of the gist.

For example, FIG. 1 shows the case where the corrosion prevention treatment layer 14 is formed on the surface of the metal foil layer 13 on the side of the second adhesive layer 17 , but the corrosion prevention treatment layer 14 is formed on the second adhesive layer 17 side of the metal foil layer 13 . It may be formed on the surface of one adhesive layer 12 side, or may be formed on both surfaces of the metal foil layer 13 . When the corrosion prevention treatment layer 14 is formed on both surfaces of the metal foil layer 13, the structure of the corrosion prevention treatment layer 14 formed on the first adhesive layer 12 side of the metal foil layer 13 and the structure of the metal foil layer 13 The structure of the corrosion prevention treatment layer 14 formed on the second adhesive layer 17 side may be the same or different.

FIG. 1 shows the case where the metal foil layer 13 and the sealant layer 16 are laminated using the second adhesive layer 17, but the power storage device exterior material 20 shown in FIG. The sealant layer 16 may be formed directly on the metal foil layer 13 without interposing the second adhesive layer 17 as in the device exterior material 30 . On the other hand, the power storage device exterior material 20 shown in FIG. 2 and the power storage device exterior material 30 shown in FIG. .

FIG. 1 shows the case where the sealant layer 16 is formed of a single layer, but the sealant layer 16 may be formed like the power storage device exterior material 20 shown in FIG. 2 and the power storage device exterior material 30 shown in FIG. It may be formed from multiple layers of two or more layers. The configuration of each of the multiple layers forming the sealant layer 16 may be the same or different. In addition, when the sealant layer 16 has multiple layers, at least one layer thereof is an ultra-high-molecular-weight polyolefin-containing layer containing ultra-high-molecular-weight polyolefin.

In the power storage device exterior material 20 shown in FIG. 2, the sealant layer 16 is composed of a first sealant layer 16a and a second sealant layer 16b. Here, the first sealant layer 16a is the outermost layer of the sealant layers, and the second sealant layer 16b is the innermost layer of the sealant layers. At least one layer selected from the group consisting of the first sealant layer 16a and the second sealant layer 16b is an ultra-high molecular weight polyolefin-containing layer containing the ultra-high molecular weight polyolefin.

The second sealant layer 16b (innermost layer) can be formed, for example, using the same components as those of the sealant layer 16 in the exterior material 10 described above. When the second sealant layer 16b is a layer containing ultra-high molecular weight polyolefin, deterioration of insulation is likely to be suppressed while maintaining lamination strength when electrolyte solution is involved.

Further, the second sealant layer 16b may be formed using a material other than ultra-high molecular weight polyolefin from the materials forming the sealant layer 16 in the exterior material 10 described above.

The thickness of the second sealant layer 16b is not particularly limited, but specifically, for example, it is preferably in the range of 5 to 100 μm, and from the viewpoint of thinning, it is in the range of 10 to 30 μm. may

The first sealant layer 16a (outermost layer, metal foil side layer) may be formed, for example, using the same components as the second sealant layer 16b. , Instead of the resin composition α as the base resin composition, a resin composition containing an adhesive resin composition as a main component and, if necessary, an additive component in consideration of aluminum treatment and adhesiveness (hereinafter referred to as a case (referred to as "resin composition β") is preferably used. That is, the first sealant layer 16a may be formed from, for example, ultra-high molecular weight polyolefin and the resin composition β, or may be formed from the resin composition β alone. When the first sealant layer 16a contains an adhesive resin composition, the sealant layer can be formed on the metal foil layer without an adhesive layer. When the first sealant layer 16a is formed from the ultra-high molecular weight polyolefin and the resin composition β, the breakage of the sealant layer due to swelling and foaming due to the electrolytic solution is easily suppressed, and the vicinity of the metal foil layer is exposed and exposed to the electrolytic solution. can be suppressed for a long period of time, the deterioration of insulation can be suppressed more efficiently.

[Resin composition β (excluding the above ultra-high molecular weight polyolefin)]
Although the adhesive resin composition in the resin composition β is not particularly limited, it preferably contains the modified polyolefin resin (a) component and the macrophase-separated thermoplastic elastomer (b) component. Further, the additive component preferably contains an atactic structure polypropylene or an atactic structure propylene-α-olefin copolymer (c). Each component will be described below.

(Modified polyolefin resin (a))
The modified polyolefin resin (a) is a resin in which an unsaturated carboxylic acid derivative component derived from any one of an unsaturated carboxylic acid, an unsaturated carboxylic acid anhydride, and an unsaturated carboxylic acid ester is graft-modified onto a polyolefin resin. is preferably

Examples of polyolefin resins include polyolefin resins such as low-density polyethylene, medium-density polyethylene, high-density polyethylene, ethylene-α-olefin copolymer, homo-, block-, or random polypropylene, and propylene-α-olefin copolymer. .

Compounds used for graft modification of these polyolefin resins include unsaturated carboxylic acid derivative components derived from any of unsaturated carboxylic acids, unsaturated carboxylic acid anhydrides, and unsaturated carboxylic acid esters. .

Specifically, examples of unsaturated carboxylic acids include acrylic acid, methacrylic acid, maleic acid, fumaric acid, itaconic acid, citraconic acid, tetrahydrophthalic acid, bicyclo[2,2,1]hept-2-ene-5, 6-dicarboxylic acid and the like.

Acid anhydrides of unsaturated carboxylic acids include, for example, maleic anhydride, itaconic anhydride, citraconic anhydride, tetrahydrophthalic anhydride, bicyclo[2,2,1]hept-2-ene-5,6-dicarboxylic anhydride. acid anhydrides of unsaturated carboxylic acids such as

Examples of unsaturated carboxylic acid esters include methyl acrylate, methyl methacrylate, ethyl methacrylate, butyl methacrylate, dimethyl maleate, monomethyl maleate, diethyl fumarate, dimethyl itaconate, diethyl citraconate, tetrahydrophthalic anhydride. Esters of unsaturated carboxylic acids such as dimethyl and dimethyl bicyclo[2,2,1]hept-2-ene-5,6-dicarboxylate are included.

The modified polyolefin resin (a) is obtained by graft polymerization (graft modification) of 0.2 to 100 parts by mass of the unsaturated carboxylic acid derivative component described above with respect to 100 parts by mass of the base polyolefin resin in the presence of a radical initiator. can be manufactured in The reaction temperature for graft modification is preferably 50 to 250°C, more preferably 60 to 200°C. In addition, the reaction time is appropriately set according to the production method. minutes is more preferred. Graft modification can be carried out under normal pressure or pressurized conditions.

Radical initiators used for graft modification include organic peroxides such as alkyl peroxides, aryl peroxides, acyl peroxides, ketone peroxides, peroxyketals, peroxycarbonates, peroxyesters and hydroperoxides. be done.

These organic peroxides can be appropriately selected and used according to the reaction temperature and reaction time conditions described above. For example, in the case of melt graft polymerization using a twin-screw extruder, alkyl peroxides, peroxyketals, and peroxyesters are preferred, and specifically di-t-butyl peroxide, 2,5-dimethyl-2,5-di -t-butylperoxy-hexyne-3, dicumyl peroxide and the like are preferred.

As the modified polyolefin resin (a), a polyolefin resin modified with maleic anhydride is preferable. Since such a modified polyolefin resin (a) component is excellent in reactivity with various metals and polymers having various functional groups, the reactivity can be used to impart adhesion to the first sealant layer 16a. It is possible to improve the electrolytic solution resistance.

The weight-average molecular weight of the modified polyolefin resin (a) is preferably 10,000 or more and less than 200,000, more preferably 50,000, from the viewpoint of obtaining the effects of adhesion and electrolyte resistance more efficiently. 000 or more and 150,000 or less.

(Macrophase-separated thermoplastic elastomer (b))
The macrophase-separated thermoplastic elastomer (b) forms a macrophase-separated structure with a dispersed phase size of more than 200 nm and 50 μm or less in the modified polyolefin resin (a).

When the adhesive resin composition contains the macrophase-separated thermoplastic elastomer (b) component, the modified polyolefin resin (a) component, which can be the main component of the first sealant layer 16a, is laminated. Residual stress can be released, and thermoelastic adhesion can be imparted to the first sealant layer 16a. Therefore, the adhesion of the first sealant layer 16a is further improved, and the exterior material 20 having excellent electrolyte resistance is obtained.

The macrophase-separated thermoplastic elastomer (b) exists in a sea-island pattern on the modified polyolefin resin (a), but if the dispersed phase size is 200 nm or less, it is difficult to improve the viscoelastic adhesion. become. On the other hand, when the dispersed phase size exceeds 50 μm, the modified polyolefin resin (a) and the macrophase-separated thermoplastic elastomer (b) are essentially incompatible, so lamination suitability (processability) is remarkably lowered. , the physical strength of the first sealant layer 16a tends to decrease. From the above, the dispersed phase size is preferably 500 nm to 10 μm.

Such a macrophase-separated thermoplastic elastomer (b) is selected from, for example, ethylene and/or propylene, 1-butene, 1-pentene, 1-hexene, 1-octene, and 4-methyl-1-pentene. Polyolefin-based thermoplastic elastomers obtained by copolymerizing α-olefins can be mentioned.

In addition, as the macrophase-separated thermoplastic elastomer (b) component, commercially available products can be used. ' etc. is suitable.

In the resin composition β, the content of the macrophase-separated thermoplastic elastomer (b) component relative to the modified polyolefin resin (a) component is 1 to 40 parts by mass with respect to 100 parts by mass of the modified polyolefin resin (a) component. is preferred, and 5 to 30 parts by mass is more preferred. If the content of the macrophase-separated thermoplastic elastomer (b) component is less than 1 part by mass, no improvement in adhesion of the first sealant layer can be expected. On the other hand, when the content of the macrophase-separated thermoplastic elastomer (b) component exceeds 40 parts by mass, the compatibility between the modified polyolefin resin (a) component and the macrophase-separated thermoplastic elastomer (b) component is originally low. The processability tends to be remarkably lowered. Further, since the macrophase-separated thermoplastic elastomer (b) component is not a resin exhibiting adhesiveness, the adhesion of the first sealant layer 16a to other layers such as the second sealant layer 16b and the corrosion prevention treatment layer 14 is low. easy to decline.

The weight-average molecular weight of the macrophase-separated thermoplastic elastomer (b) is preferably 10,000 or more and less than 200,000, and more preferably, from the viewpoint of obtaining the effects of adhesion and electrolyte resistance more efficiently. is 50,000 or more and 150,000 or less.

(Polypropylene with atactic structure or propylene-α-olefin copolymer with atactic structure (c))
The resin composition β preferably contains an atactic structure polypropylene or an atactic structure propylene-α-olefin copolymer (hereinafter simply referred to as “component (c)”) as an additive component. Here, component (c) is a completely amorphous resin component.

The effect of adding the additive component (c) to the adhesive resin composition, which is the main component of the resin composition β, will be described below.

Component (c) is compatible with the modified polyolefin resin (a) component in the adhesive resin composition in a molten state, but is expelled out of the crystals and phase-separated during crystallization accompanying cooling. Thereby, the component (c) does not inhibit the crystallinity of the modified polyolefin resin (a) component in the adhesive resin composition which is the main component. Further, by adding the component (c) to the resin composition β, the concentration of the modified polyolefin resin (a) component is diluted with the component (c), thereby suppressing the crystal growth. (That is, it is possible to reduce the crystal size (spherulite size) of the modified polyolefin resin (a) component). In addition, the component (c) discharged outside the crystals is uniformly dispersed around the microspherulites of the modified polyolefin resin (a) component.

By the way, it is conventionally known that a "whitening phenomenon" occurs when an exterior material is cold-molded. Here, the mechanism of the whitening phenomenon will be described.
(1) The modified polyolefin resin (a) in the resin composition β is crystallized by heat treatment during thermal lamination.
(2) Since the modified polyolefin resin (a) and the macrophase-separated thermoplastic elastomer (b) are incompatible, strain occurs at the interface between the two due to the crystallization behavior of (1).
(3) When stress is applied during molding, cracks occur at the interfaces between the two, forming void-crazes.
(4) Light is scattered by void-crazes, and a whitening phenomenon occurs due to optical diffuse reflection of light.

That is, in order to suppress the whitening phenomenon, "the crystallization of the modified polyolefin resin (a) should not proceed with the amount of heat during heat lamination (that is, the crystallization should be made difficult)" and "the modified polyolefin resin (a) and It is known that "improving adhesion with the macrophase-separated thermoplastic elastomer (b)" is important.

On the other hand, by adding the component (c) as an additive component to the adhesive resin composition that can be the main component of the first sealant layer 16a, the crystal size (spherulite size) of the modified polyolefin resin (a) component ) can be reduced, so flexible and tenacious film properties can be obtained. In addition, by uniformly dispersing the component (c) around the modified polyolefin resin (a), stress can be uniformly relieved, and the occurrence of void crazes can be suppressed. It is thought that it becomes possible to mitigate the "whitening phenomenon".

As described above, by adding the component (c) as an additive component to the adhesive resin composition that can be the main component of the first sealant layer 16a, the transparency of the first sealant layer 16a is increased and the molding The whitening phenomenon associated with the stress of time can be alleviated. As a result, molding whitening is also improved, and the insulating properties (bending resistance) associated with the bending stress of the exterior material 20 can be improved. In addition, flexibility can be imparted while the degree of crystallinity of the modified polyolefin resin component (a) in the first sealant layer 16a is maintained. It becomes possible.

(Isotactic structure propylene-α olefin copolymer (d))
The resin composition β further contains a propylene-α olefin copolymer having an isotactic structure (hereinafter simply referred to as “component (d)”) as an additive component in addition to the component (c) described above. You can

Here, the component (d) acts as a compatible rubber component in the adhesive resin component, which is the main component of the resin composition β, especially when the modified polyolefin resin (a) is a polypropylene-based adhesive resin. It suppresses crystallization of the modified polyolefin resin (a).

That is, by adding the component (d) as an additive component to the adhesive resin component, which is the main component of the resin composition β, flexibility for relieving stress can be imparted, so that the strength of the electrolyte laminate can be improved. It is possible to improve the heat seal strength (especially resistance to electrolytic solution) and improve the heat seal, molding and degassing heat seal strengths while suppressing the decrease. Moreover, by combining the component (c) and the component (d) as additive components, the whitening phenomenon and the resistance to bending can be further improved.

In the resin composition β, the total mass of components (a) and (b) may be, for example, 60% by mass or more and 95% by mass or less, based on the total mass of the first sealant layer 16a. It may be more than mass % and less than 90 mass %.

In the resin composition β, the total mass of component (c) and component (d) is, for example, 5 mass based on the total mass of component (a), component (b), component (c) and component (d). % or more and 40 mass % or less. The total weight of component (c) and component (d) is less than 5% by weight based on the total weight of component (a), component (b), component (c) and component (d). Additives such as these tend not to provide sufficient effects. On the other hand, when the total mass of component (c) and component (d) exceeds 40% by mass based on the total mass of component (a), component (b), component (c) and component (d), the second The adhesion of the first sealant layer 16a to other layers such as the second sealant layer 16b and the anti-corrosion treatment layer 14 tends to decrease. From these points of view, in the resin composition β, the total mass of the components (a) and (b) is based on the total mass of the components (a), (b), (c) and (d). , for example, preferably 60 to 95% by mass.

As an analytical method for component (c), which is an additive component, in resin composition β, for example, stereoregularity evaluation by nuclear magnetic resonance spectroscopy (NMR) can be used for quantitative determination.

On the other hand, for the analysis of component (d), using Fourier transform infrared spectroscopy (FT-IR), the absorber attributed to the α-olefin branch and the characteristic absorber of the modified polyolefin resin (a) The compounding ratio can be confirmed by creating a calibration curve with the absorber attributed to.

Resin composition β is an adhesive resin composition (that is, modified polyolefin resin (a) component and macrophase-separated thermoplastic elastomer (b) component) and additive components (that is, component (c) and component (d)). In addition, various additives such as flame retardants, slip agents, anti-blocking agents, antioxidants, light stabilizers, tackifiers, etc. may be contained as necessary.

The thickness of the first sealant layer 16a is not particularly limited, but is preferably equal to or less than that of the second sealant layer 16b from the viewpoint of stress relaxation and moisture/electrolyte permeation.

Also in the power storage device exterior material 20, the thickness of the sealant layer 16 (the total thickness of the first sealant layer 16a and the second sealant layer 16b) is 30 μm or less from the viewpoint of thinning. may Even with such a thin film structure, the exterior material for a power storage device of the present embodiment can suppress deterioration in insulation after heat sealing, molding, and degassing heat sealing.

FIG. 2 shows the case where the sealant layer 16 is formed of two layers, but the sealant layer 16 may be formed of three layers like the power storage device exterior material 30 shown in FIG. In the power storage device exterior material 30 shown in FIG. 3, the sealant layer 16 is composed of a first sealant layer 16a, a second sealant layer 16b, and a third sealant layer 16c. Here, the first sealant layer 16a is the outermost layer (metal foil side layer) of the sealant layer, the third sealant layer 16c is the intermediate layer of the sealant layer, and the second sealant layer 16b is the sealant layer. It is the innermost layer. At least one layer selected from the group consisting of these three layers is an ultra-high-molecular-weight polyolefin-containing layer containing the above-mentioned ultra-high-molecular-weight polyolefin.

Exemplified and preferred forms of the material constituting the first sealant layer 16 a of the power storage device exterior material 30 are the same as those of the first sealant layer 16 a of the power storage device exterior material 20 .

Exemplary and preferred forms of the materials constituting the second sealant layer 16b and the third sealant layer 16c of the power storage device exterior material 30 are the same as those of the second sealant layer 16b of the power storage device exterior material 20. FIG.

In the power storage device exterior material 30, the thickness of the first sealant layer 16a may be, for example, 2 to 30 μm, 5 to 20 μm, or 8 to 10 μm. The thickness of the sealant layer 16b may be, for example, 10 to 80 μm, 13 to 40 μm, or 15 to 20 μm, and the thickness of the third sealant layer 16c may be, for example, , 2 to 30 μm, 5 to 20 μm, or 8 to 10 μm.

Also in the power storage device exterior material 30, from the viewpoint of thinning, the thickness of the sealant layer 16 (the total thickness of the first sealant layer 16a, the second sealant layer 16b, and the third sealant layer 16c) is , 30 μm or less. Even with such a thin film structure, the exterior material for a power storage device of the present embodiment can suppress deterioration in insulation after heat sealing, molding, and degassing heat sealing.

When the sealant layer is composed of a plurality of layers like the exterior materials 20 and 30 for electric storage devices, the first sealant layer 16a closest to the metal foil layer 13 is preferably a layer containing ultra-high molecular weight polyolefin. Since the first sealant layer 16a is a layer containing ultra-high-molecular-weight polyolefin, the breakage of the sealant layer due to swelling and foaming due to the electrolytic solution is easily suppressed, and the vicinity of the metal foil layer 13 is exposed and contacts the electrolytic solution. can be suppressed for a long period of time, the deterioration of insulation can be suppressed more efficiently. When the first sealant layer 16a is an ultra-high molecular weight polyolefin-containing layer, the content of the resin composition β in the first sealant layer 16a is based on the total mass of the first sealant layer 16a, for example: It may be 40.0 to 97.0% by mass, or 50.0 to 95.0% by mass. In addition, the content of the ultra-high molecular weight polyolefin may be, for example, 3.0 to 60.0% by mass, or 5.0 to 50.0% by mass, based on the total mass of the first sealant layer 16a. or 5.0 to 30.0% by mass.

When the content of the ultra-high molecular weight polyolefin in the first sealant layer 16a is 3.0% by mass or more, deterioration of insulation can be suppressed more efficiently. Moreover, when the content of the ultra-high molecular weight polyolefin is 60.0% by mass or less, it becomes easier to suppress the deterioration of the laminate strength when the electrolytic solution is involved.

Also, the second sealant layer 16b or the third sealant layer 16c may be a layer containing ultra-high molecular weight polyolefin. Since the second sealant layer 16b or the third sealant layer 16c is an ultra-high molecular weight polyolefin-containing layer, deterioration of insulation is easily suppressed while maintaining the lamination strength in the case where the electrolytic solution is involved. When the second sealant layer 16b is an ultra-high molecular weight polyolefin-containing layer, the content of the ultra-high molecular weight polyolefin in the second sealant layer 16b is based on the total mass of the second sealant layer 16b, for example It may be 5.0 to 60.0% by mass, 15.0 to 50.0% by mass, or 30.0 to 50.0% by mass.

When the content of the ultra-high molecular weight polyolefin in the second sealant layer 16b is 5.0% by mass or more, deterioration of insulation can be suppressed more efficiently. Further, when the content of the ultra-high molecular weight polyolefin is 60.0% by mass or less, the necessary properties are satisfied, and high-speed processing becomes easier while maintaining the film formability.

The content of the ultra-high molecular weight polyolefin in the third sealant layer 16c is, based on the total mass of the third sealant layer 16c, from the same viewpoint as the second sealant layer 16b, for example 5.0 to 60. 0% by mass, 15.0 to 50.0% by mass, or 30.0 to 50.0% by mass.

Further, in both cases where the sealant layer consists of a single layer and when the sealant layer consists of a plurality of layers, the content of the above-mentioned ultra-high molecular weight polyolefin in the sealant layer is From the viewpoint of further improving the degassing heat seal strength while maintaining the electrolyte solution properties and molding whitening resistance, the total mass of the sealant layer is based on, for example, 0.1 to 0.1 to It may be 80.0% by mass, 5.0 to 60.0% by mass, or 10.0 to 35.0% by mass.

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

The method for manufacturing the exterior material 10 of the present embodiment includes a step of laminating the corrosion prevention treatment layer 14 on the metal foil layer 13, a step of bonding the base material layer 11 and the metal foil layer 13 together, and a second adhesive layer. It is roughly configured including a step of further laminating a sealant layer 16 via 17 to produce a laminated body, and a step of aging the obtained laminated body, if necessary.

(Lamination step of corrosion prevention treatment layer 14 on metal foil layer 13)
This step is a step of forming the corrosion prevention treatment layer 14 on the metal foil layer 13 . As the method, as described above, the metal foil layer 13 may be subjected to a degreasing treatment, a hydrothermal transformation treatment, an anodizing treatment, or a chemical conversion treatment, or a method of applying a coating agent having corrosion prevention performance. .

Further, when the corrosion prevention treatment layer 14 is multi-layered, for example, a coating liquid (coating agent) constituting the corrosion prevention treatment layer on the lower layer side (metal foil layer 13 side) is applied to the metal foil layer 13 and baked to form the second layer. After forming the first layer, a coating liquid (coating agent) that constitutes the upper corrosion prevention treatment layer may be applied to the first layer and baked to form the second layer.

For degreasing, the spray method or immersion method is used. For hydrothermal transformation treatment and anodizing treatment, the immersion method is used. For the chemical conversion treatment, the immersion method, spray method, coating method, etc. are appropriately selected according to the type of chemical conversion treatment. you can do it.

Various methods such as gravure coating, reverse coating, roll coating, and bar coating can be used as the coating method of the coating agent having anti-corrosion performance.

As described above, the various treatments may be applied to either one or both sides of the metal foil, but in the case of single-sided treatment, the treated side is preferably the side on which the second adhesive layer 17 is laminated. Note that the surface of the base layer 11 may also be subjected to the above-described treatment as required.

Also, the coating amount of the coating agent for forming the first layer and the second layer is preferably 0.005 to 0.200 g/m ² , more preferably 0.010 to 0.100 g/m ² .

Further, when dry curing is required, it can be carried out at a base material temperature of 60 to 300° C. depending on the drying conditions for the corrosion prevention treatment layer 14 to be used.

(Step of Bonding Base Material Layer 11 and Metal Foil Layer 13)
This step is a step of bonding the metal foil layer 13 provided with the corrosion prevention treatment layer 14 and the base layer 11 with the first adhesive layer 12 interposed therebetween. As a bonding method, dry lamination, non-solvent lamination, wet lamination, or the like is used, and both are bonded together with the material constituting the first adhesive layer 12 described above. The first adhesive layer 12 is provided in a dry coating amount of 1 to 10 g/m ² , more preferably 3 to 7 g/m ² .

(Lamination step of second adhesive layer 17 and sealant layer 16)
This step is a step of bonding the sealant layer 16 to the corrosion prevention treatment layer 14 side of the metal foil layer 13 via the second adhesive layer 17 . A wet process, a dry lamination, etc. are mentioned as the method of bonding.

In the case of a wet process, a solution or dispersion of an adhesive that constitutes the second adhesive layer 17 is applied onto the corrosion prevention treatment layer 14 and heated at a predetermined temperature (when the adhesive contains an acid-modified polyolefin resin is a temperature above its melting point) to remove the solvent and form a dry film, or after the dry film is formed, a baking treatment is performed as necessary. After that, the sealant layer 16 is laminated to manufacture the exterior material 10 . Examples of the coating method include the various coating methods exemplified above.

(Aging treatment process)
This step is a step of aging (curing) the laminate. By aging the laminate, the adhesion between the metal foil layer 13/corrosion prevention treatment layer 14/second adhesive layer 17/sealant layer 16 can be promoted. Aging treatment can be performed at room temperature to 100°C. Aging time is, for example, 1 to 10 days. Moreover, in order to bond the second adhesive layer 17 and the sealant layer 16 together, heat treatment can be performed at a temperature equal to or higher than the melting point of the second adhesive layer 17 . Examples of the heat treatment include techniques such as oven heating, sandwiching between heated rolls (thermal lamination), and winding around heated rolls, but are not limited to these.

Thus, the exterior material 10 of the present embodiment as shown in FIG. 1 can be manufactured.

Next, an example of a method for manufacturing the exterior material 20 shown in FIG. 2 will be described. Note that the method for manufacturing the exterior material 20 is not limited to the following method.

The method for manufacturing the exterior material 20 of the present embodiment includes a step of laminating the corrosion prevention treatment layer 14 on the metal foil layer 13, a step of bonding the base material layer 11 and the metal foil layer 13 together, and a first sealant layer 16a. and the second sealant layer 16b are further laminated to form a laminate, and if necessary, the obtained laminate is heat-treated. The steps up to the step of bonding the base material layer 11 and the metal foil layer 13 together can be performed in the same manner as in the method for manufacturing the exterior material 10 described above.

(Lamination step of first sealant layer 16a and second sealant layer 16b)
This step is a step of forming a first sealant layer 16a and a second sealant layer 16b on the corrosion prevention treatment layer 14 formed in the previous step. As a method thereof, there is a method of sand laminating the first sealant layer 16a together with the second sealant layer 16b using an extrusion lamination machine. Furthermore, lamination is also possible by a tandem lamination method or a co-extrusion method in which the first sealant layer 16a and the second sealant layer 16b are extruded. The resin composition for forming the first sealant layer 16a and the resin composition for forming the second sealant layer 16b are, for example, so as to satisfy the configurations of the first sealant layer 16a and the second sealant layer 16b described above. , can be prepared by blending each component.

By this process, as shown in FIG. 2, the order of base layer 11 / first adhesive layer 12 / metal foil layer 13 / corrosion prevention treatment layer 14 / first sealant layer 16a / second sealant layer 16b to obtain a laminate in which each layer is laminated.

The first sealant layer 16a may be formed by directly laminating dry-blended materials by an extrusion lamination machine so as to have the above-described material composition, or by using a single-screw extruder or a twin-screw extruder in advance. The granulated first sealant layer 16a after melt blending using a melt-kneading device such as a Brabender mixer may be laminated using an extrusion laminator.

The second sealant layer 16b may be formed by directly laminating a dry-blended material with an extrusion lamination machine so as to have the above-described material composition as the resin composition for forming the sealant layer, or by preliminarily performing single screw extrusion. The first sealant layer 16a and the second sealant layer 16b are pressed with an extrusion laminator after the granules are melt-blended using a melt-kneading device such as a machine, a twin-screw extruder, and a Brabender mixer. It may be laminated by a tandem lamination method or a co-extrusion method. In addition, using a resin composition for forming a sealant layer, a sealant single film may be formed as a cast film in advance, and this film may be laminated by a method of sand lamination with an adhesive resin, or an adhesive may be used. may be laminated by a dry lamination method.

(Heat treatment process)
This step is a step of heat-treating the laminate. By heat-treating the laminate, the adhesion between the metal foil layer 13/corrosion prevention treatment layer 14/first sealant layer 16a/second sealant layer 16b is improved, resulting in better electrolyte resistance and resistance. Hydrofluoric acid can be imparted, and the crystallization of the first sealant layer 16a and the second sealant layer 16b can be controlled to obtain the effect of improving the insulation after molding. Therefore, in this step, it is preferable to perform heat treatment suitable for crystallization of the first sealant layer 16a and the second sealant layer 16b while improving the adhesion between the layers described above. As the method, the contents described above are mentioned, but it is preferable to perform the treatment at a temperature equal to or higher than the melting point of at least the first sealant layer 16a.

In this way, the exterior material 20 of this embodiment as shown in FIG. 2 can be manufactured.

Next, an example of a method for manufacturing the exterior material 30 shown in FIG. 3 will be described. Note that the method for manufacturing the exterior material 30 is not limited to the following method.

The method for manufacturing the exterior material 30 of the present embodiment includes a step of laminating the corrosion prevention treatment layer 14 on the metal foil layer 13, a step of bonding the base material layer 11 and the metal foil layer 13 together, and a first sealant layer 16a. , a step of further laminating the third sealant layer 16c and the second sealant layer 16b to produce a laminate, and, if necessary, a step of heat-treating the obtained laminate. .

(Lamination step of first sealant layer 16a, third sealant layer 16c and second sealant layer 16b)
This step is a step of forming a first sealant layer 16 a , a third sealant layer 16 c and a second sealant layer 16 b on the corrosion prevention treatment layer 14 . Examples of the method include a tandem lamination method and a co-extrusion method in which the first sealant layer 16a, the third sealant layer 16c and the second sealant layer 16b are extruded using an extrusion laminator. In this case, the resin composition for forming the sealant layer may be dry-blended so as to have the above-described material composition, and may be directly laminated by an extrusion laminator, or may be laminated in advance by a single-screw extruder or twin-screw extruder. The granulated material after being melt-blended using a melt-kneading device such as a machine, a Brabender mixer, etc., is subjected to an extrusion lamination machine to form the first sealant layer 16a, the third sealant layer 16c, and the second sealant layer 16b. may be laminated by a tandem lamination method or a co-extrusion method.

The third sealant layer 16c and the second sealant layer 16b may be formed by co-extrusion, and these films may be laminated together with the resin composition for forming the first sealant layer 16a by sand lamination.

In this way, the exterior material 30 of this embodiment as shown in FIG. 3 can be manufactured.

Preferred embodiments of the exterior material for a power storage device of the present invention have been described above in detail. Various modifications and changes are possible within the scope of the gist. For example, when manufacturing an exterior material for a power storage device that does not have the first adhesive layer 12, a resin material capable of forming the base layer 11 is applied or coated onto the metal foil layer 13 as described above. Thus, the base material layer 11 may be formed.

The power storage device exterior material of the present invention is suitable as, for example, a secondary battery such as a lithium ion battery, a nickel metal hydride battery, and a lead storage battery, and an electrical storage device such as an electrochemical capacitor such as an electric double layer capacitor. can be used. Among others, the exterior material for a power storage device of the present invention is suitable as an exterior material for a lithium ion battery.

EXAMPLES The present invention will be described in more detail based on examples below, but the present invention is not limited to the following examples.

[Materials used]
Materials used in Examples and Comparative Examples are shown below.
<Base material layer (thickness 15 μm)>
A nylon film (Ny) (manufactured by Toyobo Co., Ltd.) was used.

<First adhesive layer (thickness 4 μm)>
A polyurethane-based adhesive (manufactured by Toyo Ink Co., Ltd.) in which a tolylene diisocyanate adduct-based curing agent was blended with a polyester polyol-based main agent was used.

<First corrosion prevention treatment layer (base material layer side) and second corrosion prevention treatment layer (sealant layer side)>
(CL-1): "Sodium polyphosphate-stabilized cerium oxide sol" adjusted to a solid concentration of 10% by mass using distilled water as a solvent was used. The sodium polyphosphate-stabilized cerium oxide sol was obtained by blending 10 parts by mass of Na salt of phosphoric acid with 100 parts by mass of cerium oxide.
(CL-2): 90% by mass of “polyallylamine (manufactured by Nittobo Co., Ltd.)” adjusted to a solid content concentration of 5% by mass using distilled water as a solvent, and “polyglycerol polyglycidyl ether (manufactured by Nagase ChemteX Corporation)” A composition consisting of 10% by weight was used.
(CL-3): Using an aqueous phosphoric acid solution with a concentration of 1% by mass as a solvent, chromium fluoride (CrF ₃ ) is added to a water-soluble phenolic resin (manufactured by Sumitomo Bakelite Co., Ltd.) adjusted to a solid content concentration of 1% by mass. A chemical conversion treatment agent was used whose concentration was adjusted so that the amount of Cr present in the dry film was 10 mg/m ² .

<Metal foil layer (thickness 35 μm)>
Annealed and degreased soft aluminum foil (“8079 material” manufactured by Toyo Aluminum Co., Ltd.) was used.

<Second adhesive layer (thickness 3 μm)>
As the adhesive for forming the second adhesive layer, the following adhesives a and b were prepared.
Adhesive a: An adhesive obtained by blending 10 parts by mass (solid content ratio) of a polyisocyanate compound having an isocyanurate structure with 100 parts by mass of a maleic anhydride-modified polyolefin resin dissolved in toluene.
Adhesive b: A polyurethane-based adhesive obtained by blending a polyester polyol composed of a hydrogenated dimer fatty acid and a diol with a polyisocyanate so that the molar ratio (NCO/OH) is 2.

<Sealant layer>
[Base resin composition]
As a base resin composition for forming a sealant layer, the following resins A, B, C, D and E were prepared.

(Resin A): A mixture obtained by mixing the following materials at a mass ratio of (AR-1):(AR-2)=75:25. This mixture corresponds to the resin composition β.
(AR-1): Acid-modified polypropylene resin composition based on random polypropylene (PP) (Mw: 130,000, Mw/Mn: 5) containing ethylene-propylene rubber as an incompatible rubber.
(AR-2): A propylene-α olefin copolymer with an atactic structure.

(Resin B): A resin composition obtained by mixing the following materials at a mass ratio of (A):(B-1):(B-2)=70:20:10. This mixture corresponds to the resin composition α.
(A): Propylene-ethylene random copolymer (random PP) (Mw: 150,000, Mw/Mn: 6).
(B-1): Propylene-butene-1 random copolymer elastomer (propylene-butene-1) having a melting point of 85° C. and compatible with component (A).
(B-2): Ethylene-butene-1 random copolymer elastomer (ethylene-butene-1) having a melting point of 75° C. and having no compatibility with component (A).

Resin C: Linear low-density polyethylene (LLDPE)-based acid-modified polyethylene resin composition (Mw: 120,000, Mw/Mn: 5).

Resin D: A resin composition obtained by mixing the following materials at a mass ratio of (D-1):(D-2):(D-3)=70:20:10.
(D-1): Linear low-density polyethylene (LLDPE) (Mw: 100,000, Mw/Mn: 5).
(D-2): Ethylene-butene-1 random copolymer elastomer (ethylene-butene-1) having a melting point of 75°C (same as component (B-2) above).
(D-3): Propylene-butene-1 random copolymer elastomer (propylene-butene-1) having a melting point of 85°C (same as component (B-1) above).

Resin E: A random polypropylene (PP)-based, acid-modified polypropylene resin composition containing ethylene-propylene rubber as an incompatible rubber (same as component (AR-1) above). This resin composition corresponds to the resin composition β.

[Ultra-high molecular weight polyolefin]
F-1-1: Propylene-ethylene random copolymer (random PP) (Mw: 500,000, Mw/Mn: 9).
F-1-2: Random PP (Mw: 1,500,000, Mw/Mn: 10).
F-2: Propylene-ethylene block copolymer (block PP) (Mw: 800,000, Mw/Mn: 9).
F-3: Propylene homopolymer (homo PP) (Mw: 300,000, Mw/Mn: 8).
F-4: High density polyethylene (HDPE) (Mw: 900,000, Mw/Mn: 8).

[Example 1]
First, the metal foil layer was provided with the first and second corrosion prevention treatment layers by the following procedure. Specifically, (CL-1) was applied to both surfaces of the metal foil layer by microgravure coating so that the dry coating amount was 70 mg/m ² , and baked at 200° C. in a drying unit. Next, (CL-2) was applied onto the obtained layer by micro gravure coating so that the dry coating amount was 20 mg/m ² to obtain a composite of (CL-1) and (CL-2). The layers were formed as first and second corrosion protection layers. This composite layer exhibits anti-corrosion performance by combining two types (CL-1) and (CL-2).

Next, the metal foil layer provided with the first and second corrosion prevention treatment layers is dry-laminated on the side of the first corrosion prevention treatment layer, using a polyurethane adhesive (first adhesive layer). pasted on the material layer. This is set in the unwinding section of an extrusion laminating machine, and co-extruded on the second corrosion prevention treatment layer under the processing conditions of 290 ° C. and 100 m / min to form a sealant layer on the metal foil side (hereinafter referred to as "AL (also referred to as "side layer") (thickness 10 µm) and the innermost layer (thickness 20 µm) were laminated in this order. For the AL side layer and the innermost layer, a compound of various materials was prepared in advance using a twin-screw extruder, and the compound was subjected to water cooling and pelletizing steps before being used in the extrusion laminate. A mixture of resin A (corresponding to resin composition β) and ultrahigh molecular weight polyolefin F-1-1 was used to form the AL side layer. The content of the ultra-high molecular weight polyolefin F-1-1 in the AL side layer was 5% by mass based on the total mass of the AL side layer (corresponding to the sealant layer 16a). Resin B (corresponding to resin composition α) was used to form the innermost layer (corresponding to sealant layer 16b).

The laminate thus obtained was heat-treated so that the maximum temperature reached by the laminate was 190° C., and the exterior material of Example 1 (base material layer/first adhesive layer/second A laminate of one anti-corrosion treatment layer/metal foil layer/second anti-corrosion treatment layer/AL side layer (sealant layer 16a)/innermost layer (sealant layer 16b)) was manufactured. In this embodiment, the AL side layer (sealant layer 16a) is a layer containing ultra-high molecular weight polyolefin.

[Example 2]
The content of the ultra-high molecular weight polyolefin F-1-1 in the AL side layer (sealant layer 16a) was set to 15% by mass based on the total mass of the AL side layer (sealant layer 16a). The exterior material of Example 2 was produced in the same manner as in Example 1. In this embodiment, the AL side layer (sealant layer 16a) is a layer containing ultra-high molecular weight polyolefin.

[Example 3]
The content of the ultra-high molecular weight polyolefin F-1-1 in the AL side layer (sealant layer 16a) was set to 30% by mass based on the total mass of the AL side layer (sealant layer 16a). An exterior material of Example 3 was produced in the same manner as in Example 1. In this embodiment, the AL side layer (sealant layer 16a) is a layer containing ultra-high molecular weight polyolefin.

[Example 4]
The content of the ultra-high molecular weight polyolefin F-1-1 in the AL side layer (sealant layer 16a) was set to 50% by mass based on the total mass of the AL side layer (sealant layer 16a). An exterior material of Example 4 was produced in the same manner as in Example 1. In this embodiment, the AL side layer (sealant layer 16a) is a layer containing ultra-high molecular weight polyolefin.

[Example 5]
The material used to form the AL side layer (sealant layer 16a) was changed to resin A (resin composition β), and the material used to form the innermost layer (sealant layer 16b) was changed to resin B (resin composition An exterior material of Example 5 was produced in the same manner as in Example 1, except that the mixture was changed to a mixture of product α) and ultrahigh molecular weight polyolefin F-1-1. The content of ultra-high molecular weight polyolefin F-1-1 in the innermost layer was set to 5% by mass based on the total mass of the innermost layer (sealant layer 16b). In this embodiment, the innermost layer (sealant layer 16b) is a layer containing ultra-high molecular weight polyolefin.

[Example 6]
The content of ultra-high molecular weight polyolefin F-1-1 in the innermost layer (sealant layer 16b) was 15% by mass based on the total mass of the innermost layer (sealant layer 16b), except that Example 5 and In the same manner, an exterior material of Example 6 was produced. In this embodiment, the innermost layer (sealant layer 16b) is a layer containing ultra-high molecular weight polyolefin.

[Example 7]
The content of the ultra-high molecular weight polyolefin F-1-1 in the innermost layer (sealant layer 16b) was set to 30% by mass based on the total mass of the innermost layer (sealant layer 16b). In the same manner, an exterior material of Example 7 was produced. In this embodiment, the innermost layer (sealant layer 16b) is a layer containing ultra-high molecular weight polyolefin.

[Example 8]
The content of the ultra-high molecular weight polyolefin F-1-1 in the innermost layer (sealant layer 16b) was set to 50% by mass based on the total mass of the innermost layer (sealant layer 16b). In the same manner, an exterior material of Example 8 was produced. In this embodiment, the innermost layer (sealant layer 16b) is a layer containing ultra-high molecular weight polyolefin.

[Example 9]
In the same manner as in Example 1, except that the material used to form the innermost layer (sealant layer 16b) was changed to a mixture of resin B (resin composition α) and ultrahigh molecular weight polyolefin F-1-1. , the exterior material of Example 9 was manufactured. The content of the ultra-high molecular weight polyolefin F-1-1 in the innermost layer (sealant layer 16b) was 5% by mass based on the total mass of the innermost layer (sealant layer 16b). In this embodiment, the AL side layer (sealant layer 16a) and the innermost layer (sealant layer 16b) are ultra-high molecular weight polyolefin-containing layers.

[Example 10]
The content of ultra-high molecular weight polyolefin F-1-1 in the AL side layer (sealant layer 16a) is set to 15% by mass based on the total mass of the AL side layer (sealant layer 16a), and the innermost layer Same as Example 9, except that the content of ultra-high molecular weight polyolefin F-1-1 in (sealant layer 16b) was set to 15% by mass based on the total mass of the innermost layer (sealant layer 16b). Thus, an exterior material of Example 10 was manufactured. In this embodiment, the AL side layer (sealant layer 16a) and the innermost layer (sealant layer 16b) are ultra-high molecular weight polyolefin-containing layers.

[Example 11]
The content of ultra-high molecular weight polyolefin F-1-1 in the AL side layer (sealant layer 16a) is set to 30% by mass based on the total mass of the AL side layer (sealant layer 16a), and the innermost layer The same as in Example 9 except that the content of ultra-high molecular weight polyolefin F-1-1 in (sealant layer 16b) was set to 30% by mass based on the total mass of the innermost layer (sealant layer 16b). Thus, an exterior material of Example 11 was manufactured. In this embodiment, the AL side layer (sealant layer 16a) and the innermost layer (sealant layer 16b) are ultra-high molecular weight polyolefin-containing layers.

[Example 12]
The content of ultra-high molecular weight polyolefin F-1-1 in the AL side layer (sealant layer 16a) is set to 50% by mass based on the total mass of the AL side layer (sealant layer 16a), and the innermost layer The same procedure as in Example 9 was performed except that the content of ultra-high molecular weight polyolefin F-1-1 in (sealant layer 16b) was set to 50% by mass based on the total mass of the innermost layer (sealant layer 16b). Thus, the exterior material of Example 12 was manufactured. In this embodiment, the AL side layer (sealant layer 16a) and the innermost layer (sealant layer 16b) are ultra-high molecular weight polyolefin-containing layers.

[Example 13]
The content of ultra-high molecular weight polyolefin F-1-1 in the AL side layer (sealant layer 16a) was set to 60% by mass based on the total mass of the AL side layer (sealant layer 16a), and the innermost layer Same as Example 9, except that the content of ultra-high molecular weight polyolefin F-1-1 in (sealant layer 16b) was set to 60% by mass based on the total mass of the innermost layer (sealant layer 16b). Thus, an exterior material of Example 13 was manufactured. In this embodiment, the AL side layer (sealant layer 16a) and the innermost layer (sealant layer 16b) are ultra-high molecular weight polyolefin-containing layers.

[Example 14]
In the same manner as in Example 1, the metal foil layer was provided with the first and second corrosion prevention treatment layers. The first corrosion prevention treatment layer side of the metal foil layer provided with the first and second corrosion prevention treatment layers is dry-laminated to the base layer using a polyurethane adhesive (first adhesive layer). pasted. This is set in the unwinding part of an extrusion laminating machine, and co-extruded on the second corrosion prevention treatment layer under the processing conditions of 290 ° C. and 100 m / min as a sealant layer AL side layer (sealant layer 16a) (thickness 10 μm thick), an intermediate layer (sealant layer 16c) (10 μm thick) and an innermost layer (sealant layer 16b) (10 μm thick) were laminated in this order. In addition, the AL side layer (sealant layer 16a), the intermediate layer (sealant layer 16c) and the innermost layer (sealant layer 16b) are prepared in advance by using a twin-screw extruder to prepare compounds of various materials, followed by water cooling and pelletizing. It was used for the above-mentioned extrusion lamination through the process of . Resin A (resin composition β) is used to form the AL side layer (sealant layer 16a), and resin B (resin composition α) and ultra-high molecular weight polyolefin F-1 are used to form the intermediate layer (sealant layer 16c). -1 was used, and resin B (resin composition α) was used to form the innermost layer (sealant layer 16b). The content of ultra-high molecular weight polyolefin F-1-1 in the intermediate layer (sealant layer 16c) was set to 30% by mass based on the total mass of the intermediate layer (sealant layer 16c).

The laminate thus obtained was heat-treated by thermal lamination so that the maximum temperature of the laminate was 190° C., and the exterior material of Example 14 (base layer/first adhesive Laminate of layer/first corrosion prevention treatment layer/metal foil layer/second corrosion prevention treatment layer/AL side layer (sealant layer 16a)/intermediate layer (sealant layer 16c)/innermost layer (sealant layer 16b)) manufactured. In this embodiment, the intermediate layer (sealant layer 16c) is a layer containing ultra-high molecular weight polyolefin.

[Example 15]
The same as in Example 14 except that the material used to form the AL side layer (sealant layer 16a) was changed to a mixture of resin A (resin composition β) and ultrahigh molecular weight polyolefin F-1-1. Thus, the exterior material of Example 15 was manufactured. The content of the ultra-high molecular weight polyolefin F-1-1 in the AL side layer (sealant layer 16a) was 30% by mass based on the total mass of the AL side layer (sealant layer 16a). In this embodiment, the AL side layer (sealant layer 16a) and the intermediate layer (sealant layer 16c) are ultra-high molecular weight polyolefin-containing layers.

[Example 16]
The material used to form the AL side layer (sealant layer 16a) was changed to a mixture of resin A (resin composition β) and ultrahigh molecular weight polyolefin F-1-1, and the intermediate layer (sealant layer 16c) The material used for formation was changed to resin B (resin composition α), and the material used to form the innermost layer (sealant layer 16b) was resin B (resin composition α) and ultra-high molecular weight polyolefin F- An exterior material of Example 16 was produced in the same manner as in Example 14, except that it was changed to a mixture with 1-1. The content of ultra-high molecular weight polyolefin F-1-1 in the AL side layer (sealant layer 16a) is 30% by mass based on the total mass of the AL side layer (sealant layer 16a), and the innermost layer (sealant The content of the ultra-high molecular weight polyolefin F-1-1 in the layer 16b) was 30% by mass based on the total mass of the innermost layer (sealant layer 16b). In this embodiment, the AL side layer (sealant layer 16a) and the innermost layer (sealant layer 16b) are ultra-high molecular weight polyolefin-containing layers.

[Example 17]
The material used to form the AL side layer (sealant layer 16a) was changed to a mixture of resin C and ultra-high molecular weight polyolefin F-4, and the material used to form the innermost layer (sealant layer 16b) was changed to resin An exterior material of Example 17 was manufactured in the same manner as in Example 1, except for changing to D. The content of the ultra-high molecular weight polyolefin F-4 in the AL side layer (sealant layer 16a) was 30% by mass based on the total mass of the AL side layer (sealant layer 16a). In this embodiment, the AL side layer (sealant layer 16a) is a layer containing ultra-high molecular weight polyolefin.

[Example 18]
In the same manner as in Example 1, except that the resin used to form the AL side layer (sealant layer 16a) was changed to a mixture of resin A (resin composition β) and ultrahigh molecular weight polyolefin F-2. A cladding material of Example 18 was produced. The content of the ultra-high molecular weight polyolefin F-2 in the AL side layer (sealant layer 16a) was 30% by mass based on the total mass of the AL side layer (sealant layer 16a). In this embodiment, the AL side layer (sealant layer 16a) is a layer containing ultra-high molecular weight polyolefin.

[Example 19]
In the same manner as in Example 1, except that the resin used to form the AL side layer (sealant layer 16a) was changed to a mixture of resin A (resin composition β) and ultrahigh molecular weight polyolefin F-3. A cladding material of Example 19 was produced. The content of ultra-high molecular weight polyolefin F-3 in the AL side layer (sealant layer 16a) was set to 30% by mass based on the total mass of the AL side layer (sealant layer 16a). In this embodiment, the AL side layer (sealant layer 16a) is a layer containing ultra-high molecular weight polyolefin.

[Example 20]
Same as Example 1 except that the resin used for forming the AL side layer (sealant layer 16a) was changed to a mixture of resin E (resin composition β) and ultrahigh molecular weight polyolefin F-1-1. Thus, an exterior material of Example 20 was manufactured. The content of the ultra-high molecular weight polyolefin F-1-1 in the AL side layer (sealant layer 16a) was 30% by mass based on the total mass of the AL side layer (sealant layer 16a). In this embodiment, the AL side layer (sealant layer 16a) is a layer containing ultra-high molecular weight polyolefin.

[Example 21]
First, the metal foil layer was provided with the first and second corrosion prevention treatment layers by the following procedure. That is, (CL-3) was applied to both surfaces of the metal foil layer by microgravure coating so that the dry coating amount was 30 mg/m ² , and baked at 200° C. in a drying unit. Next, (CL-2) was applied onto the obtained layer by microgravure coating so that the dry coating amount was 20 mg/m ² to obtain a composite of (CL-3) and (CL-2). The layers were formed as first and second corrosion protection layers. This composite layer exhibits anti-corrosion performance by combining two types (CL-3) and (CL-2). An exterior material of Example 21 was produced in the same manner as in Example 3, except that the metal foil layer provided with the first and second corrosion prevention treatment layers in this way was used. In this embodiment, the AL side layer (sealant layer 16a) is a layer containing ultra-high molecular weight polyolefin.

[Example 22]
First, the metal foil layer was provided with the first and second corrosion prevention treatment layers by the following procedure. That is, (CL-3) was applied to both surfaces of the metal foil layer by micro gravure coating so that the dry coating amount was 30 mg/m ² , and baked at 200°C in a drying unit to obtain the second layer. First and second corrosion protection layers were formed. An exterior material was produced in the same manner as in Example 3, except that the metal foil layer provided with the first and second corrosion prevention treatment layers in this way was used. In this embodiment, the AL side layer (sealant layer 16a) is a layer containing ultra-high molecular weight polyolefin.

[Example 23]
In the same manner as in Example 1, the metal foil layer was provided with the first and second corrosion prevention treatment layers. The first corrosion prevention treatment layer side of the metal foil layer provided with the first and second corrosion prevention treatment layers is dry-laminated to the base layer using a polyurethane adhesive (first adhesive layer). pasted. Then, the second corrosion prevention treatment layer side of the metal foil layer provided with the first and second corrosion prevention treatment layers is dry laminated using an adhesive a (second adhesive layer) to form a sealant layer 16. (Innermost layer) (thickness: 30 μm). A mixture of resin B (base resin composition, resin composition α) and ultrahigh molecular weight polyolefin F-1-1 was used to form the innermost layer (sealant layer 16). The content of the ultra-high molecular weight polyolefin F-1-1 in the innermost layer (sealant layer 16) was 30% by mass based on the total mass of the innermost layer (sealant layer 16).

The laminate thus obtained was subjected to aging treatment at 40 ° C. for 4 days, and the exterior material of Example 23 (base material layer / first adhesive layer / first corrosion prevention treatment layer / A laminate of metal foil layer/second anti-corrosion treatment layer/second adhesive layer/innermost layer (sealant layer 16)) was produced. In this embodiment, the innermost layer (sealant layer 16) is a layer containing ultra-high molecular weight polyolefin.

[Example 24]
An exterior material of Example 24 was produced in the same manner as in Example 23, except that the adhesive used to form the second adhesive layer was changed to adhesive b. In this embodiment, the innermost layer (sealant layer 16) is a layer containing ultra-high molecular weight polyolefin.

[Comparative Example 1]
An exterior material of Comparative Example 1 was produced in the same manner as in Example 1, except that ultra-high molecular weight polyolefin was not used, that is, Resin A was used to form the AL side layer.

[Comparative Example 2]
The procedure was the same as in Example 3, except that the resin used to form the AL side layer (sealant layer 16a) was changed to a mixture of resin A (resin composition β) and ultrahigh molecular weight polyolefin F-1-2. Thus, an exterior material of Comparative Example 2 was manufactured. The content of the ultra-high molecular weight polyolefin F-1-2 in the AL side layer (sealant layer 16a) was 30% by mass based on the total mass of the AL side layer (sealant layer 16a). In this embodiment, the AL side layer (sealant layer 16a) is a layer containing ultra-high molecular weight polyolefin.

Table 1 shows the main conditions of each example and comparative example.

<Evaluation>
The following evaluation tests were performed on the exterior materials obtained in Examples and Comparative Examples.

(High-speed workability)
The high-speed workability when the sealant layer was laminated by an extrusion laminator in the manufacture of the exterior material was evaluated according to the following criteria. For Examples 23 and 24, high-speed workability was evaluated when the sealant layer was formed alone.
A: At a temperature of 290° C. and a speed of 100 m/min, a film having a thickness of 30 μm can be formed without any problem.
D: At a temperature of 290° C. and a speed of 100 m/min, a film having a thickness of 30 μm cannot be formed without problems (thickness varies, etc.).

(Fish eye)
The following criteria evaluated the fish eye which arose in the sealant layer formed in exterior material manufacture.
A: The number of fish eyes with a diameter of 0.5 μm or more existing in the sealant layer formed to a thickness of 30 μm is 2/m ² or less.
D: The number of fisheyes having a diameter of 0.5 μm or more in the sealant layer formed to a thickness of 30 μm is 3/m ² or more.

(Electrolyte lamination strength)
A Teflon (registered trademark) container is filled with an electrolytic solution obtained by adding LiPF ₆ to a mixed solution of ethylene carbonate / diethyl carbonate / dimethyl carbonate = 1/1/1 (mass ratio) so that it becomes 1 M, and an exterior material is placed therein. was cut into 15 mm×100 mm, and stored at 85° C. for 24 hours after sealing. After that, they were co-washed, and the lamination strength (T-peel strength) between the metal foil layer/second adhesive layer or between the metal foil layer/sealant layer was measured using a tester (manufactured by INSTRON). The test was conducted in accordance with JIS K6854 at a peel rate of 50 mm/min under an atmosphere of 23° C. and 50% RH. Based on the results, evaluation was made according to the following criteria.
A: Laminate strength is over 7N/15mm B: Laminate strength is 6N/15mm or more and 7N/15mm or less C: Lamination strength is 5N/15mm or more and less than 6N/15mm D: Lamination strength is less than 5N/15mm

(Electrolyte heat seal strength)
A sample obtained by cutting the exterior material to 60 mm×120 mm was folded in two, and one side was heat-sealed with a seal bar having a width of 10 mm at 190° C., 0.5 MPa, and 3 sec. After that, LiPF ₆ was added to a mixed solution of ethylene carbonate/diethyl carbonate/dimethyl carbonate = 1/1/1 (mass ratio) to a bag-shaped exterior material by heat-sealing the remaining two sides so that the concentration became 1M. After storing the pouch into which 2 ml of the electrolytic solution was injected at 60 ° C. for 24 hours, the first heat-sealed side was cut to a width of 15 mm (see FIG. 4), and the seal strength (T-shaped peel strength) was measured with a tester (INSTRON company). The test was conducted in accordance with JIS K6854 at a peel rate of 50 mm/min under an atmosphere of 23° C. and 50% RH. Based on the results, evaluation was made according to the following criteria.
A: Seal strength is 50 N/15 mm or more, burst width is over 5 mm B: Seal strength is 50 N/15 mm or more, burst width is 3 to 5 mm
C: Seal strength of 40 N/15 mm or more and less than 50 N/15 mm D: Seal strength of less than 40 N/15 mm

(High temperature heat seal strength)
A sample obtained by cutting the exterior material to 60 mm×120 mm was folded in two, and one side was heat-sealed with a seal bar having a width of 10 mm at 190° C., 0.5 MPa, and 3 sec. After that, the heat-sealed first side was cut to a width of 15 mm (see FIG. 5), and the seal strength (T-shaped peel strength) was measured using a tester (manufactured by INSTRON) after storage at 80° C. for 1 minute. . The test was conducted at a temperature of 80° C. and a peeling speed of 50 mm/min according to JIS K6854. Based on the results, evaluation was made according to the following criteria.
A: Seal strength is 45 N/15 mm or more, burst width is over 5 mm B: Seal strength is 45 N/15 mm or more, burst width is 3 to 5 mm
C: Seal strength of 40 N/15 mm or more and less than 45 N/15 mm D: Seal strength of less than 40 N/15 mm

(Degassing heat seal strength (degas heat seal strength))
A sample of the packaging material cut to 75 mm×150 mm was folded in half to 37.5 mm×150 mm (see FIG. 6(a)), and then one of the 150 mm side and the 37.5 mm side was heat-sealed to form a bag. After that, 5 ml of an electrolytic solution obtained by adding LiPF ₆ to 1 M to a mixed solution of ethylene carbonate/diethyl carbonate/dimethyl carbonate = 1/1/1 (mass ratio) was injected into the pouch, and The other was heat-sealed to obtain a pouch sealed by the seal portion S1. Next, after storing this pouch at 60° C. for 24 hours, the central portion of the pouch containing the electrolyte was heat-sealed at 190° C., 0.3 MPa, and 2 sec (degassing heat sealing portion S2, FIG. 6(b) )). In order to stabilize the seal portion, after storage at room temperature for 24 hours, the area including the degassing heat seal portion S2 was cut to a width of 15 mm (see FIG. 6(c)), and the heat seal strength (T-shaped peel strength ) was measured using a tester (manufactured by INSTRON). The test was conducted in accordance with JIS K6854 at a peel rate of 50 mm/min under an atmosphere of 23° C. and 50% RH. Based on the results, evaluation was made according to the following criteria.
A: The seal strength is 50 N/15 mm or more B: The seal strength is 35 N/15 mm or more and less than 50 N/15 mm C: The seal strength is 25 N/15 mm or more and less than 35 N/15 mm D: The seal strength is less than 25 N/15 mm

(Whitening after molding)
A normal sample of the exterior material and a sample stored at 60 ° C. for 1 week were cut into 120 mm × 200 mm, set in a mold for cold molding so that the sealant layer was in contact with the convex part of the molding machine, molding speed 5 mm / Deep drawing of 2.0 mm was performed in sec. After that, whitening was observed on the side of the film holding portion where stretching was the most severe. The mold used had a molding area of 80 mm×70 mm (rectangular cylindrical shape) and a punch corner radius (RCP) of 1.0 mm. Based on the results, evaluation was made according to the following criteria. If the evaluation is C or higher, it can be said that there is no practical problem.
A: No whitening in both the normal sample and the sample stored at 60 ° C for 1 week B: No whitening in the normal sample, thin whitening in the sample stored at 60 ° C for 1 week C: Light whitening in the normal sample, stored at 60 ° C for 1 week Whitening in sample D: Whitening in normal sample

(Insulation after heat sealing and molding (heat sealing and molding insulation))
A sample 40 obtained by cutting the exterior material to 120 mm × 200 mm was set in a cold molding mold so that the sealant layer was in contact with the convex part of the molding machine, and deep drawing was performed to 2.0 mm at a molding speed of 15 mm / sec. After forming the deep-drawn portion 41, it was folded in two to 120 mm×100 mm (see FIG. 7(a)). Next, with the tab 42 and the tab sealant 43 sandwiched between them, the 100 mm upper side portion 44 was heat-sealed (see FIG. 7(b)), and then the 120 mm side portion 45 was heat-sealed to form a bag. (See FIG. 7(c)). After that, in order to contact the electrode, part of the outer layer of the sample 40 was shaved to form an exposed portion 46 of the metal foil layer (see FIG. 7(d)). Next, 5 ml of an electrolytic solution obtained by adding LiPF ₆ to 1 M to a mixed solution of ethylene carbonate/diethyl carbonate/dimethyl carbonate = 1/1/1 (mass ratio) was poured into the pouch, and the lower side of 100 mm was poured. 47 was sealed by heat sealing (see FIG. 7(e)). Then, after being stored in an oven at 60° C. for one week, the electrodes 48a and 48b were connected to the tab 42 and the exposed portion 46 of the metal foil layer, respectively, and a withstand voltage/insulation resistance tester (manufactured by KIKUSUI, "TOS9201") was used. A voltage of 25 V was applied to the substrate, and the resistance value at that time was measured (see FIG. 7(f)). The mold used had a molding area of 80 mm×70 mm (rectangular cylindrical shape) and a punch corner radius (RCP) of 1.0 mm. Based on the results, evaluation was made according to the following criteria.
A: Resistance value is over 200 MΩ B: Resistance value is 100 MΩ or more and 200 MΩ or less C: Resistance value is 30 MΩ or more and less than 100 MΩ D: Resistance value is less than 30 MΩ

(Insulation after degassing heat sealing (degassing insulation))
A sample 50 obtained by cutting an exterior material to 75 mm×150 mm was folded in half to 37.5 mm×150 mm (see FIG. 8(a)). Next, with the tab 52 and the tab sealant 53 sandwiched between them, the upper side portion 54 of 37.5 mm is heat-sealed (see FIG. 8(b)), and then the side portion 55 of 150 mm is heat-sealed. bagged (see FIG. 8(c)). After that, in order to contact the electrode, part of the outer layer of the sample 50 was shaved to form an exposed portion 56 of the metal foil layer (see FIG. 8(d)). Next, 5 ml of an electrolytic solution obtained by adding LiPF ₆ to 1 M to a mixed solution of ethylene carbonate/diethyl carbonate/dimethyl carbonate = 1/1/1 (mass ratio) was injected into the pouch, and The lower side portion 57 was sealed by heat sealing (see FIG. 8(e)). After that, the pouch was laid flat and left at 60° C. for 24 hours, and the central portion 58 of the pouch containing the electrolytic solution was degassed and heat-sealed at 190° C., 0.3 MPa (surface pressure), and 2 seconds. . Next, electrodes 59a and 59b are connected to the tab 52 and the exposed portion 56 of the metal foil layer, respectively, and a voltage of 25 V is applied using a withstand voltage/insulation resistance tester ("TOS9201" manufactured by KIKUSUI), and the resistance value at that time is was measured (see FIG. 8(f)). Based on the results, evaluation was made according to the following criteria.
A: Resistance value is over 200 MΩ B: Resistance value is 100 MΩ or more and 200 MΩ or less C: Resistance value is 30 MΩ or more and less than 100 MΩ D: Resistance value is less than 30 MΩ

(Total quality)
Table 2 shows the results of each of the above evaluations. In Table 2 below, it can be said that the overall quality is excellent if there is no D rating in each evaluation result.

As is clear from the results shown in Table 2, it was confirmed that the exterior materials of Examples 1 to 24 had excellent insulation properties after heat sealing, molding, and degassing heat sealing. Furthermore, the exterior materials of Examples 1 to 24 have a small number of fish eyes in the sealant layer, high-speed workability, electrolyte lamination strength, electrolyte heat seal strength, high temperature heat seal strength, degassing heat seal strength, It was confirmed that it had sufficient performance even in molding whitening, and that it also had excellent insulation properties after heat sealing and molding.

Furthermore, when comparing Examples 1 to 4 and Comparative Example 1, it was found that the addition of ultra-high molecular weight polyolefin to the sealant layer improved the insulation properties after degassing heat sealing, and that further improvement was achieved by increasing the amount added. I can confirm. On the other hand, it can be confirmed that the deterioration of the electrolytic solution lamination strength could be suppressed by not excessively increasing the amount of ultra-high molecular weight polyolefin added to the AL side layer.

Comparing Examples 5 to 8 and Comparative Example 1, by adding ultra-high molecular weight polyolefin to the innermost layer, although the foaming origin cannot be completely suppressed, by increasing the amount added, the degassing after heat sealing It can be confirmed that the insulation has improved.

By comparing Examples 9 to 13 and Examples 1 to 8, it can be confirmed that the addition of ultra-high molecular weight polyolefin to both the AL side layer and the innermost layer also improved the insulation after degassing heat sealing.

Comparing Examples 14 to 16, when the sealant layer consists of three or more layers, by adding an ultra-high molecular weight polyolefin closer to the AL side, the insulation after degassing heat sealing was easily improved. I can confirm.

By comparing Examples 17 to 19 and Example 3, it can be confirmed that the type of ultra-high molecular weight polyolefin to be added made a difference in the evaluations other than the insulating property after degassing heat sealing.

Comparing Example 20 and Example 3, it can be confirmed that by changing the base resin composition of the AL side layer, a difference was produced in evaluations other than insulation properties after degassing heat sealing.

Comparing Example 21 and Example 3, it can be confirmed that the difference in the composition of the corrosion prevention treatment layer caused a difference in evaluations other than insulation. Comparing Example 22 and Example 3, it can be confirmed that there was a difference in all evaluations other than high-speed workability, number of fish eyes, and high-temperature seal strength.

From the evaluation results of Examples 23 and 24, it can be confirmed that the performance can be similarly improved even when the sealant layer is provided by the dry lamination method. It can be confirmed that there is a difference in the evaluation depending on the type of adhesive.

In Comparative Example 2, it can be confirmed that the weight average molecular weight of the added ultra-high molecular weight polyolefin was large, the high-speed workability was lowered, and the number of fish eyes in the sealant layer was increased. As a result, it was not possible to evaluate the characteristics in the battery manufacturing process.

DESCRIPTION OF SYMBOLS 10, 20, 30... Exterior material for electrical storage apparatus 11... Base material layer 12... First adhesive layer 13... Metal foil layer 14... Corrosion prevention treatment layer 16... Sealant layer 16a... First layer Sealant layer 16b Second sealant layer 16c Third sealant layer 17 Second adhesive layer 40 Sample 41 Deep drawn portion 42 Tab 43 Tab sealant 44 Upper edge Part, 45... Side part, 46... Exposed part of metal foil layer, 47... Lower side part, 48a, 48b... Electrode, 50... Sample, 52... Tab, 53... Tab sealant, 54... Upper side part, 55... Side side Portion 56 Exposed portion of metal foil layer 57 Lower side portion 58 Center portion 59a, 59b Electrode S1 Seal portion S2 Degassing heat seal portion.

Claims (10)

An exterior material for a power storage device, comprising at least a base material layer, a metal foil layer provided with a corrosion prevention treatment layer on one or both surfaces, and a sealant layer in this order,
The exterior material for a power storage device, wherein the sealant layer has a weight average molecular weight of 2.0×10 ⁵ to 1.0×10 ⁶ and contains an ultra-high molecular weight polyolefin having a molecular weight distribution of 6 to 10 . 2. The exterior material for a power storage device according to claim 1, wherein the content of said ultra-high molecular weight polyolefin in said sealant layer is 5.0 to 50.0% by mass based on the total mass of said sealant layer. 3. The exterior material for a power storage device according to claim 1, wherein said sealant layer comprises a plurality of layers, at least one of which is a layer containing said ultra-high molecular weight polyolefin. 3. The exterior material for a power storage device according to claim 1, wherein said sealant layer comprises a plurality of layers, of which the layer closest to said metal foil layer is a layer containing said ultra-high molecular weight polyolefin. 5. The exterior material for a power storage device according to claim 4, wherein the layer closest to the metal foil layer is a layer further containing an acid-modified polypropylene and an atactic structure polypropylene or an atactic structure propylene-α olefin copolymer. . 6. The exterior material for a power storage device according to claim 1, wherein said ultra-high molecular weight polyolefin contains ultra-high molecular weight polypropylene. 7. The exterior material for a power storage device according to claim 6, wherein said ultra-high molecular weight polypropylene contains ultra-high molecular weight random polypropylene. further comprising an adhesive layer between the metal foil layer and the sealant layer;
The adhesive layer contains an acid-modified polyolefin, and at least one curing agent selected from the group consisting of a polyfunctional isocyanate compound, a glycidyl compound, a compound having a carboxy group, a compound having an oxazoline group, and a carbodiimide compound. The exterior material for a power storage device according to any one of claims 1 to 7. 9. Any one of claims 1 to 8, wherein the anti-corrosion treatment layer contains cerium oxide, 1 to 100 parts by mass of phosphoric acid or a phosphate with respect to 100 parts by mass of the cerium oxide, and a cationic polymer. 1. The exterior material for a power storage device according to item 1. 2. The corrosion prevention treatment layer is formed by subjecting the metal foil layer to chemical conversion treatment, or is formed by subjecting the metal foil layer to chemical conversion treatment and contains a cationic polymer. 9. The exterior material for a power storage device according to any one of items 1 to 8.

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