JP7102683B2 - Exterior material for power storage equipment - Google Patents

Description

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

As the power storage device, for example, a secondary battery such as a lithium ion battery, a nickel hydrogen battery, and a lead storage battery, and an electrochemical capacitor such as an electric double layer capacitor are known. Further miniaturization of power storage devices is required due to miniaturization of portable devices or restrictions on installation space, and lithium ion batteries having high energy density are attracting attention. Conventionally, metal cans have been used as the exterior material used for lithium-ion batteries, but a multilayer film (for example, base material layer / metal leaf layer /) that is lightweight, has high heat dissipation, and can be produced at low cost. A film having a structure similar to that of a sealant layer) has come to be used.

In a lithium ion battery using the multilayer film as an exterior material, in order to prevent moisture from entering the inside, a configuration is adopted in which the battery contents are covered with an exterior material containing an aluminum foil layer as a metal foil layer. A lithium ion battery adopting such a configuration is called an aluminum laminate type lithium ion battery. The battery contents of the lithium ion battery include a positive electrode, a negative electrode, a separator, and a lithium salt as an electrolyte in an aprotonic solvent having penetrating power such as propylene carbonate, ethylene carbonate, dimethyl carbonate, diethyl carbonate, and ethyl methyl carbonate. An electrolyte layer made of a dissolved electrolyte or a polymer gel impregnated with the electrolyte is included.

In an aluminum-laminated lithium-ion battery, for example, a recess is formed in a part of the exterior material by cold molding, the battery contents are housed in the recess, and the remaining part of the exterior material is folded back to heat the edge portion. An embossed lithium-ion battery sealed with a seal is known. It is required that the exterior material constituting such a lithium ion battery exhibits stable sealing performance by heat sealing, and that the electrolytic solution of the battery contents does not easily reduce the lamination strength between the aluminum foil layer and the sealant layer. ing.

Further, with the miniaturization of the power storage device, the base material layer, the metal foil layer and the sealant layer of the exterior material for the power storage device are being thinned, but here, the insulating property is deteriorated due to the thinning of the sealant layer. Is a problem.

Deterioration of insulation 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 parts that should not be fused during heat sealing are fused ( Hereinafter referred to as "over-adhesion"), destruction of the sealant layer by degassing heat seal, and the like.

Therefore, for example, in Patent Document 1, by providing a heat seal layer (sealant layer) including an adhesive polymethylpentene layer, the barrier layer and the tab of the exterior body are stabilized without being short-circuited by the heat and pressure of the heat seal. An exterior material that can be sealed is proposed.

Japanese Unexamined Patent Publication No. 2002-245983

In the conventional exterior material as described in Patent Document 1, measures are taken to reduce the insulating property due to the contact between the tab lead and the metal foil layer. However, the verification by the present inventors has not examined the destruction of the sealant layer due to over-adhesion or degassing heat seal, which is considered to be the most important measure for improving the insulating property.

The present inventors speculate that the decrease in insulating property due to over-adhesion is caused by the formation of cracks when stress is applied because the over-attached portion is in a non-uniform crystalline state. .. Further, in the degassing heat seal, since the above-mentioned electrolytic solution is bitten and heat-sealed, it is presumed that the cause is that the electrolytic solution foams and the sealant layer is destroyed. It is considered that the electrolytic solution enters from the cracks and the destroyed sealant layer portion generated by these and comes into contact with the metal layer, so that the insulating property is lowered.

Further, the deterioration of the insulating property caused by the formation of cracks due to over-adhesion during heat sealing and the destruction of the sealant layer due to the degassing heat sealing is easily affected by the thinning of the sealant layer, and thus is insulated. Among the sexual improvements, special measures will be required in the future.

The present invention has been made in view of the above-mentioned problems of the prior art, and can sufficiently maintain the insulating property 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 object, the present invention includes at least a base material layer, a metal foil layer provided with a corrosion prevention treatment layer on one or both surfaces, an adhesive layer or an adhesive resin layer, and a sealant layer. An exterior material for a power storage device having a structure laminated in order, wherein the sealant layer provides an exterior material for a power storage device containing a single-site catalytic polypropylene resin.

According to the exterior material for a power storage device having the above configuration, even when the sealant layer is thinned, the insulating property after heat sealing, molding and degassing heat sealing can be sufficiently maintained. According to the exterior material for a power storage device, sufficient insulating properties can be maintained even when the sealant layer is deformed due to heat during sealing or stress during molding. The present inventors speculate the reason why the exterior material for a power storage device exerts such an effect as follows.

The sealant layer of the exterior material for a power storage device undergoes many deformations that accompany volume changes such as swelling, crystallization, and stretching of the electrolytic solution in the process of manufacturing the power storage device such as heat sealing, degassing heat sealing, and molding. Prone to defects. In particular, due to the thinning of the sealant layer, in the degassing heat seal in which the electrolytic solution is bitten and heat-sealed, the deformation of the sealant layer, which is considered to be due to the volatilization (foaming) of the electrolytic solution, becomes large and the insulating property is improved. Easy to drop. It is conceivable that the reason why the insulating property is lowered due to the deformation is that, for example, the vicinity of the metal foil layer is easily exposed by foaming, and the electrolytic solution comes into contact with the exposed portion. In addition, cracks may be formed in the sealant layer due to over-adhesion (excessive sealing portion) generated during heat sealing, and the electrolytic solution may permeate into the cracks to reduce the insulating property. Over-adhesion is a phenomenon in which a portion of the sealant layer that should not be sealed is fused by heat during heat-sealing. When over-adhesion occurs in the sealant layer, the crystallinity changes due to slow cooling after heat sealing, and the over-density part becomes low-density, and stress is applied to this low-density part to form cracks, resulting in insulating properties. It is easy to cause a decrease. Furthermore, due to the thinning of the sealant layer, 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 a decrease in insulating property after molding. ..

On the other hand, by using the single-site catalytic polypropylene resin for the sealant layer, the occurrence of the above-mentioned problems can be suppressed, and the deterioration of the insulating property can be suppressed. The single-site catalytic polypropylene has a narrower molecular weight distribution than the commonly used multi-site catalytic polypropylene, and has very few low molecular weight components and low crystal components. Therefore, since there are few low molecular weight components and low crystal components, the above-mentioned sealant layer is less likely to be over-adhered, and the crystallinity of the heat-sealed portion becomes uniform, so that crack formation is suppressed and the insulating property is improved. Improve. Further, since the single-site catalytic polypropylene has a narrow molecular weight distribution, the formation of tie molecules is promoted and the toughness is increased. Therefore, deformation and destruction of the sealant layer due to foaming of the electrolytic solution during degassing heat sealing are suppressed, and the insulating property is improved. Further, since the single-site catalytic polypropylene has a small amount of low crystal components, the crystallization becomes uniform and dense, the electrolytic solution is less likely to swell in the sealant layer, and the electrolytic solution is less likely to foam. Therefore, foaming of the electrolytic solution at the time of degassing heat sealing is suppressed, and the insulating property is improved. In addition, since the single-site catalytic polypropylene has high toughness, various sealing strengths can be improved, and cracks can be suppressed from being generated in the sealant layer due to stress during cold molding or the like. Even with a top seal that heat-seals multiple materials such as tab sealant and metal tab at the same time, the insulation property is likely to decrease due to cracks. However, by using the above single-site catalytic polypropylene resin for the sealant layer, , It is possible to prevent cracks from being generated in the sealant layer at the time of top sealing. From the above, according to the exterior material for a power storage device of the present invention, even when the sealant layer is thinned, the insulating property after heat sealing, molding and degassing heat sealing can be sufficiently maintained.

In the exterior material for a power storage device, the single-site catalytic polypropylene resin preferably contains a propylene-ethylene random copolymer.

Homopolypropylene, random polypropylene, or block polypropylene can be used as the single-site catalytic polypropylene resin. Among them, random polypropylene (propylene-ethylene random copolymer) allows deep drawability (moldability). In addition, the strength of various seals can be further improved, and molding whitening can be further suppressed.

In the exterior material for a power storage device, the sealant layer is made of a propylene-α-olefin copolymer which is a compatible elastomer having compatibility with the single-site catalytic polypropylene resin and the single-site catalytic polypropylene resin. On the other hand, at least one of the ethylene-α-olefin copolymer, which is an incompatible elastomer having no compatibility, may be further contained.

By adding a compatible elastomer, the sealant layer can be made flexible. By giving the sealant layer flexibility, it is possible to impart functions such as molding whitening resistance and impact resistance to the sealant layer, and it is possible to provide an exterior material with further improved functionality. Further, the propylene-α-olefin copolymer can further improve the sealing properties in which the electrolytic solution is involved, such as the electrolytic solution laminating strength and the degassing heat sealing strength. On the other hand, by adding an incompatible elastomer, impact resistance and cold resistance can be imparted to the sealant layer. Further, the ethylene-α-olefin copolymer can further improve the sealing properties in which the electrolytic solution is involved, such as the electrolytic solution laminating strength and the degassing heat sealing strength. In addition, only one of these two types of compatible elastomers and incompatible elastomers may be added, but when both are used in combination, the molding whitening resistance and the sealing property in which the electrolytic solution is involved should be improved in a well-balanced manner. Can be done.

Here, at least one of the propylene-α-olefin copolymer and the ethylene-α-olefin copolymer may be a single-site catalytic elastomer.

The above-mentioned elastomer can be obtained from either a multi-site catalyst or a single-site catalyst, but a single-site catalyst-based elastomer having a narrow molecular weight distribution and a small amount of low molecular weight components can be used. More preferred. By using the single-site catalytic elastomer, it is possible to suppress deterioration of the insulating property after heat sealing, molding and degassing heat sealing.

In the exterior material for a power storage device, the adhesive resin layer may contain acid-modified polypropylene and polypropylene having an atactic structure or a propylene-α-olefin copolymer having an atactic structure. As a result, it becomes easy to suppress a decrease in the laminate strength and a decrease in the insulating property when the electrolytic solution is involved.

In the exterior material for a power storage device, the adhesive layer is at least one selected from the group consisting of an acid-modified polyolefin, a polyfunctional isocyanate compound, a glycidyl compound, a compound having a carboxy group, a compound having an oxazoline group, and a carbodiimide compound. It may contain a seed hardener. As a result, it becomes easy to suppress a decrease in the laminate strength and a decrease in the insulating property when the electrolytic solution is involved.

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

According to the present invention, it is possible to provide an exterior material for a power storage device capable of sufficiently maintaining the insulating property after heat sealing, molding and degassing heat sealing even when the sealant layer is thinned. The exterior material for a power storage device of the present invention has a thin film structure, for example, even if the total thickness on the inner layer side of the metal foil layer provided with the corrosion prevention treatment layer is 35 μm or less, heat sealing, molding, and degapping. Sufficient insulation can be maintained after sing heat sealing.

It is the schematic sectional drawing of the exterior material for a power storage device which concerns on one Embodiment of this invention. It is the schematic sectional drawing of the exterior material for a power storage device which concerns on one Embodiment of this invention. It is a schematic diagram explaining the method of making the evaluation sample in an Example. It is a schematic diagram explaining the method of making the evaluation sample in an Example. It is a schematic diagram explaining the method of making the evaluation sample in an Example.

Hereinafter, preferred embodiments of the present invention will be described in detail with reference to the drawings. In the drawings, the same or corresponding parts are designated by the same reference numerals, and duplicate description will be omitted. Moreover, the dimensional ratio of the drawing is not limited to the ratio shown in the drawing.

The exterior material for the power storage device of the present embodiment has at least a base material layer, a metal foil layer provided with a corrosion prevention treatment layer on one or both surfaces, an adhesive layer or an adhesive resin layer, and a sealant layer in this order. The sealant layer contains a single-site catalytic polypropylene resin. Hereinafter, the exterior material for the power storage device of the present embodiment will be described with reference to some embodiments.

[Exterior material for power storage device]
FIG. 1 is a cross-sectional view schematically showing an embodiment of an exterior material for a power storage device according to this 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) formed on one surface of the base material layer 11. (Sometimes referred to as the adhesive layer 12), the metal foil layer 13 formed on the surface of the first adhesive layer 12 opposite to the base material layer 11, and the first of the metal foil layer 13. An anticorrosion-treated layer 14 formed on a surface opposite to the adhesive layer 12, an adhesive resin layer 15 formed on a surface opposite to the metal foil layer 13 of the anticorrosion-treated layer 14, and the like. This is a laminated body in which the sealant layer 16 formed on the surface of the adhesive resin layer 15 opposite to the corrosion prevention treatment layer 14 is 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. Hereinafter, each layer will be described.

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

The thickness of the base material layer 11 is preferably 6 to 40 μm, more preferably 10 to 25 μm. When the thickness of the base material layer 11 is 6 μm or more, the pinhole resistance and the insulating property of the exterior material 10 for a power storage device tend to be improved.

The base material layer 11 may be provided by directly applying it on the metal foil layer 13 described later. In this case, the first adhesive layer 12 described later is unnecessary. As a method for forming the base material layer by coating, a method of applying a resin coating liquid such as urethane resin, acrylic resin, polyester resin and the like and curing by ultraviolet irradiation, high temperature heating, aging (curing) treatment or the like can be adopted. When the resin coating liquid is a urethane resin, specifically, for example, a polyurethane resin obtained by reacting a main agent such as a polyester polyol, a polyether polyol, an acrylic polyol, or a carbonate polyol with a bifunctional or higher functional isocyanate compound 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 adopted.

<First adhesive layer 12>
The first adhesive layer 12 is a layer for adhering the base material layer 11 and the metal foil layer 13. Specific examples of the material constituting the first adhesive layer 12 include polyurethane obtained by reacting a main agent such as a polyester polyol, a polyether polyol, an acrylic polyol, or a carbonate polyol with a bifunctional or higher functional isocyanate compound. Examples include resin.

The various polyols described above can be used alone or in combination of two or more, depending on the function and performance required for the exterior material.

Further, for the purpose of promoting adhesion, a carbodiimide compound, an oxazoline compound, an epoxy compound, a phosphorus compound, a silane coupling agent and the like may be added to the above-mentioned polyurethane resin.

Further, various other additives and stabilizers may be added to the above-mentioned polyurethane resin 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, preferably 3 to 7 μm, from the viewpoint of obtaining desired adhesive strength, followability, processability, and the like. More preferred.

<Metal leaf layer 13>
The metal foil layer 13 has a water vapor barrier property that prevents moisture from entering the inside of the power storage device. Further, the metal foil layer 13 has ductility for deep drawing molding. As the metal foil layer 13, various metal foils such as aluminum, stainless steel, and copper can be used, and aluminum foil is preferable from the viewpoints of mass (specific gravity), moisture resistance, workability, and cost.

As the aluminum foil, a soft aluminum foil that has been subjected to a quenching treatment can be particularly preferably used from the viewpoint of imparting a desired ductility during molding, but further pinhole resistance and ductility during molding are imparted. For the purpose, it is more preferable to use aluminum foil containing iron. The iron content 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, the exterior material 10 having more excellent pinhole resistance and ductility can be obtained. When the iron content is 9.0% by mass or less, the exterior material 10 having more excellent flexibility can be obtained.

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 from the viewpoint 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 due to the electrolytic solution or hydrofluoric acid generated by the reaction between the electrolytic solution and water. The corrosion prevention treatment layer 14 is formed by, for example, a degreasing treatment, a hydrothermal transformation treatment, an anodization treatment, a chemical conversion treatment, or a combination of these treatments.

Examples of the degreasing treatment include acid degreasing and alkaline degreasing. Examples of the acid degreasing include a method in which an inorganic acid such as sulfuric acid, nitric acid, hydrochloric acid, or hydrofluoric acid is used alone, or a mixed solution thereof is used. Further, as the acid degreasing, by using an acid degreasing agent in which a fluorine-containing compound such as monosodium difluoride is dissolved in the above-mentioned inorganic acid, aluminum degreasing is performed particularly when an aluminum foil is used for the metal foil layer 13. Not only is it effective, but it can also form an immobilized aluminum fluoride, which is effective in terms of acid resistance. Examples of the alkaline degreasing include a method using sodium hydroxide and the like.

Examples of the hot water transformation treatment include a boehmite treatment in which an aluminum foil is immersed in boiling water to which triethanolamine is added.

Examples of the anodizing treatment include alumite treatment.

Examples of the chemical conversion treatment include a dipping type and a coating type. Examples of the immersion type chemical conversion treatment include chromate treatment, zirconium treatment, titanium treatment, vanadium treatment, molybdenum treatment, calcium phosphate treatment, strontium hydroxide treatment, cerium treatment, ruthenium treatment, and various chemical conversion treatments consisting of a mixed phase thereof. Be done. On the other hand, as a coating type chemical conversion treatment, a method of coating a coating agent having corrosion prevention performance on the metal foil layer 13 can be mentioned.

Of these corrosion prevention treatments, when at least a part of the corrosion prevention treatment layer is formed by any of the hydrothermal transformation treatment, the anodizing treatment, and the chemical conversion treatment, it is preferable to perform the above-mentioned degreasing treatment in advance. When a degreased metal foil such as a metal foil that has undergone an annealing step is used as the metal foil layer 13, it is necessary to perform degreasing treatment again in forming the corrosion prevention treatment layer 14. Yes.

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

Further, among the above treatments, particularly in the hydrothermal transformation treatment and the anodizing treatment, the surface of the aluminum foil is dissolved by the treatment agent to form aluminum compounds (boehmite, alumite) having excellent corrosion resistance. Therefore, a co-continuous structure is formed from the metal foil layer 13 using the aluminum foil to the corrosion prevention treatment layer 14, and 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 sol of a rare earth element oxide such as cerium oxide having an average particle size of 100 nm or less is used as a material having an anticorrosion effect (inhibitor effect) of aluminum and also being environmentally suitable. The method to be used can be mentioned. By using this method, it is possible to impart a corrosion prevention effect to a metal foil such as an aluminum foil even with 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 sol. Of these, aqueous sol is preferable.

In the sol of the rare earth element oxide, inorganic acids such as nitrate, hydrochloric acid and phosphoric acid or salts thereof, and organic acids such as acetic acid, apple acid, ascorbic acid and lactic acid are usually dispersed and stabilized in order to stabilize the dispersion. Used as an agent. 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 the adhesion to the metal foil layer 13 by utilizing the aluminum chelating ability of phosphoric acid. , (3) Improving electrolyte resistance by capturing (immobilizing) aluminum ions eluted by the influence of hydrofluoric acid, (4) Corrosion prevention treatment layer 14 due to the tendency to cause dehydration condensation of phosphoric acid even at low temperatures (4) It is expected that the cohesive force of the oxide layer) will be improved.

Examples of the phosphoric acid or a salt thereof include orthophosphoric acid, pyrophosphoric acid, metaphosphoric acid, and alkali metal salts and ammonium salts thereof. Of these, condensed phosphoric acids such as trimetaphosphoric acid, tetramethaphosphoric acid, hexametaphosphoric acid, and ultramethaphosphoric acid, or alkali metal salts and ammonium salts thereof are preferable for functional expression in the exterior material 10. Further, considering the dry film-forming property (drying capacity, calorific value) when the corrosion prevention treatment layer 14 made of the rare earth element oxide is formed by various coating methods using the sol of the rare earth element oxide, at a low temperature. Sodium salts are more preferable because they are excellent in dehydration condensate. As the phosphate, a water-soluble salt is preferable.

The blending ratio of phosphoric acid (or a salt thereof) to the rare earth element oxide is preferably 1 to 100 parts by mass with respect to 100 parts by mass 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 erosion of the electrolytic solution is excellent. The compounding ratio is more preferably 50 parts by mass or less, still more preferably 20 parts by mass or less, based on 100 parts by mass of the rare earth element oxide.

Since the corrosion prevention treatment layer 14 formed by the rare earth element oxide sol is an aggregate of inorganic particles, the cohesive force of the layer itself may decrease even after the drying cure step. Therefore, in this case, the corrosion prevention treatment layer 14 is preferably composited with the following anionic polymer or cationic polymer in order to supplement the cohesive force.

Examples of the anionic polymer include polymers having a carboxy group, and examples thereof include poly (meth) acrylic acid (or a salt thereof) and a copolymer obtained by copolymerizing poly (meth) acrylic acid as a main component. As the copolymerization component of this copolymer, an alkyl (meth) acrylate-based monomer (as an alkyl group, a methyl group, an ethyl group, an n-propyl group, an i-propyl group, an n-butyl group, an i-butyl group, etc. t-butyl group, 2-ethylhexyl group, cyclohexyl group, etc.); (meth) acrylamide, N-alkyl (meth) acrylamide, N, N-dialkyl (meth) acrylamide (alkyl groups include methyl group, ethyl group, etc.) 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-dialkyl (Meta) acrylamide, (alkyl groups include methoxy group, ethoxy group, butoxy group, isobutoxy group, etc.), N-methylol (meth) acrylamide, N-phenyl (meth) acrylamide and other amide group-containing monomers; 2- 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 acryloxipropyltriethoxylan; isocyanate group-containing monomers such as (meth) acryloxypropyl isocyanate and the like can be mentioned.

These anionic polymers play a role in improving the stability of the corrosion prevention treatment layer 14 (oxide layer) obtained by using the rare earth element oxide sol. This is due to the effect of protecting the hard and brittle oxide layer with an acrylic resin component and the effect of capturing ion contamination (particularly sodium ions) derived from phosphate contained in the rare earth element oxide sol (cation catcher). Achieved. That is, when the corrosion prevention treatment layer 14 obtained by using the rare earth element oxide sol contains alkali metal ions such as sodium or alkaline earth metal ions, corrosion prevention starts from the place containing these ions. The treated layer 14 is likely to deteriorate. Therefore, the resistance of the corrosion prevention treatment layer 14 is improved by immobilizing sodium ions and the like contained in the rare earth element oxide sol with the anionic polymer.

The corrosion prevention treatment layer 14 in which the anionic polymer and the rare earth element oxide sol are combined has the same corrosion prevention performance as the corrosion prevention treatment layer 14 formed by subjecting the aluminum foil to chromate treatment. The anionic polymer preferably has a structure in which an essentially water-soluble polyanionic polymer is crosslinked. Examples of the cross-linking agent used for forming this structure include compounds having an isocyanate group, a glycidyl group, a carboxy group, and an oxazoline group.

Examples of the compound having an isocyanate group include tolylene diisocyanate, xylylene diisocyanate or a hydrogenated product thereof, hexamethylene diisocyanate, 4,4'diphenylmethane diisocyanate or a hydrogenated product thereof, diisocyanates such as isophorone diisocyanate; or these isocyanates. Polyisocyanates such as adducts obtained by reacting with polyhydric alcohols such as trimethylolpropane, burettes obtained by reacting with water, or isocyanurates which are trimeric; or polyisocyanates thereof. Examples thereof include blocked polyisocyanates in which isocyanates are blocked with alcohols, lactams, oximes and the like.

Examples of the compound having a glycidyl group include ethylene glycol, diethylene glycol, triethylene glycol, polyethylene glycol, propylene glycol, dipropylene glycol, tripropylene glycol, polypropylene glycol, 1,4-butanediol, and 1,6-hexanediol. Glycols such as neopentyl glycol and epoxy compounds on which epichlorohydrin is allowed to act; polyhydric alcohols such as glycerin, polyglycerin, trimethylolpropane, pentaerythritol, sorbitol and epoxy compounds on which epichlorohydrin is allowed to act; phthalic acid, terephthalate Examples thereof include an epoxy compound obtained by reacting dicarboxylic acids such as acid, oxalic acid and adipic acid with epichlorohydrin.

Examples of the compound having a carboxy group include various aliphatic or aromatic dicarboxylic acids. Further, an alkali (earth) metal salt of poly (meth) acrylic acid or poly (meth) acrylic acid may be used.

Examples of the compound having an oxazoline group include a low molecular weight compound having two or more oxazoline units, or a (meth) acrylic acid or a (meth) acrylic acid alkyl ester when a polymerizable monomer such as isopropenyl oxazoline is used. , (Meta) Acrylic monomers such as hydroxyalkyl acrylate are copolymerized.

Further, the anionic polymer and the silane coupling agent may be reacted, and more specifically, the carboxy group of the anionic polymer and the functional group of the silane coupling agent may be selectively reacted, and the cross-linking point may be 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 and the like can be used. Of these, epoxysilane, aminosilane, and isocyanatesilane are preferable, particularly considering the reactivity with the anionic polymer or its copolymer.

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 with respect to 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, the cross-linked structure is sufficiently likely to be formed. When 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 for cross-linking the anionic polymer is not limited to the above-mentioned cross-linking agent, and may be a method for forming an ionic cross-link using a titanium or zirconium compound.

Examples of the cationic polymer include an amine-containing polymer, which includes polyethyleneimine, an ionic polymer complex composed of polyethyleneimine and a polymer having a carboxylic acid, and a primary amine-grafted acrylic resin in which a primary amine is grafted on an acrylic main skeleton. Examples thereof include polyallylamine or derivatives thereof, and cationic polymers such as aminophenol.

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 carboxy group or a glycidyl group. As the cross-linking agent used in combination with the cationic polymer, a polymer having a carboxylic acid forming an ionic polymer complex with polyethyleneimine can also be used, and for example, a polycarboxylic acid (salt) such as polyacrylic acid or an ionic salt thereof, or a polycarboxylic acid (salt) thereof. Examples thereof include a copolymer in which a comonomer is introduced into the polymer, a polysaccharide having a carboxy group such as carboxymethyl cellulose or an ionic salt thereof, and the like. Examples of polyallylamine include homopolymers or copolymers such as allylamine, allylamine amide sulfate, diallylamine, and dimethylallylamine. These amines may be free amines or may be stabilized with acetic acid or hydrochloric acid. Moreover, maleic acid, sulfur dioxide and the like may be used as a copolymer component. Further, a type in which thermal crosslinkability is imparted by partially methoxylating a primary amine can be used, and aminophenol can also be used. In particular, allylamine or a derivative thereof is preferable.

In this embodiment, the cationic polymer is also described as one component constituting the corrosion prevention treatment layer 14. The reason for this is that as a result of diligent studies using various compounds to impart the electrolyte resistance and hydrofluoric acid resistance required for exterior materials for power storage devices, the cationic polymer itself also has electrolyte resistance and hydrofluoric acid resistance. This is because it was found to be a compound that can be imparted. It is presumed that this factor is because the aluminum foil is suppressed from being damaged by supplementing the fluorine ions with a cationic group (anion catcher).

Cationic polymers are more preferred materials in terms of improved adhesion. Further, since the cationic polymer is also water-soluble like the anionic polymer, it is more preferable to form a crosslinked structure to impart water resistance. As the cross-linking agent for forming the cross-linked structure on 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 instead of the anionic polymer as the protective layer thereof.

In order to form an inclined structure with the aluminum foil, the corrosion prevention treatment layer by the chemical conversion treatment represented by the chromate treatment uses a chemical conversion treatment agent containing hydrofluoric acid, hydrochloric acid, nitric acid, sulfuric acid or salts thereof, and the aluminum foil is used. Is then treated, and then a chromium or non-chromate compound is allowed to act on the aluminum foil to form a chemical conversion treatment layer. However, since the chemical conversion treatment uses an acid as the chemical conversion treatment agent, the working environment is deteriorated and the coating device is corroded. On the other hand, unlike the chemical conversion treatment represented by the chromate treatment, the coating type corrosion prevention treatment layer 14 described above does not need to form an inclined structure with respect to the metal foil layer 13 using the aluminum foil. Therefore, the properties of the coating agent are not restricted by acidity, alkalinity, neutrality, etc., and a good working environment can be realized. In addition, the coating type corrosion prevention treatment layer 14 is preferable for the chromate treatment using a chromium compound from the viewpoint that an alternative plan is required in terms of environmental hygiene.

From the above, as examples of the combination of coating type corrosion prevention treatments 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 polymers (multilayer), (7) (rare earth element oxide sol + cationic polymer: laminated composite) / anionic polymer (multilayer), and the like can be mentioned. Of these, (1) and (4) to (7) are preferable, and (4) to (7) are particularly preferable. However, this embodiment is not limited to the above combination. For example, as an example of selection of corrosion prevention treatment, the cationic polymer has good adhesiveness to the modified polyolefin resin described later in the description of the adhesive resin layer or the adhesive layer (second adhesive layer). However, since it is a very preferable material, when the adhesive resin layer or the adhesive layer is composed of a modified polyolefin resin, a cationic polymer is provided on the surface in contact with the adhesive resin layer or the adhesive layer (for example, Configurations (configurations such as (5) and (6)) can be designed.

Further, the corrosion prevention treatment layer 14 is not limited to the above-mentioned layer. For example, it may be formed by using a treatment agent in which a phosphoric acid and a chromium compound are mixed in a resin binder (aminophenol or the like), such as coating type chromate which is a known technique. By using this treatment agent, it is possible to obtain a layer having both a corrosion prevention function and adhesion. In addition, although it is necessary to consider the stability of the coating liquid, a coating agent in which the rare earth element oxide sol and the polycationic polymer or the polyanionic polymer are preliminarily liquefied is used for both corrosion prevention function and adhesion. It can be a layer that combines.

The mass per unit area of the corrosion prevention treatment layer 14 is preferably 0.005 to 0.200 g / m ² and more preferably 0.010 to 0.100 g / m ² regardless of whether it is a multilayer structure or a single layer structure. preferable. When the mass per unit area is 0.005 g / m ² or more, it is easy to impart the corrosion prevention function to the metal foil layer 13. Further, 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 due to heat during drying may be insufficient, and the cohesive force may be lowered. The thickness of the corrosion prevention treatment layer 14 can be converted from its specific gravity.

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

<Adhesive resin layer 15>
The adhesive resin layer 15 is roughly configured to include an adhesive resin composition as a main component and, if necessary, an additive component. The adhesive resin composition is not particularly limited, but preferably contains the modified polyolefin resin (a) component and the macrophase-separated thermoplastic elastomer (b) component. Further, the additive component preferably contains polypropylene having an atactic structure or a propylene-α-olefin copolymer (c) having an atactic structure. Hereinafter, each component will be described.

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

Examples of the polyolefin resin include low-density polyethylene, medium-density polyethylene, high-density polyethylene, ethylene-α-olefin copolymer, homo, block, or polyolefin resin such as random polypropylene and propylene-α-olefin copolymer. .. Of these, polypropylene-based resins are preferable.

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

Specifically, as unsaturated carboxylic acids, for example, 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 can be mentioned.

Examples of the acid anhydride of the unsaturated carboxylic acid include maleic anhydride, itaconic anhydride, citraconic anhydride, tetrahydrophthalic anhydride, and bicyclo [2,2,1] hept-2-ene-5,6-dicarboxylic acid anhydride. Examples thereof include acid anhydrides of unsaturated carboxylic acids such as substances.

Examples of the ester of unsaturated carboxylic acid include methyl acrylate, methyl methacrylate, ethyl methacrylate, butyl methacrylate, dimethyl maleate, monomethyl maleate, diethyl fumarate, dimethyl itacone, diethyl citraconate, and tetrahydrophthalic anhydride. Examples thereof include esters of unsaturated carboxylic acids such as dimethyl and dimethyl bicyclo [2,2,1] hept-2-ene-5,6-dicarboxylic acid.

In the modified polyolefin resin (a), 0.2 to 100 parts by mass of the above-mentioned unsaturated carboxylic acid derivative component is graft-polymerized (graft-modified) with respect to 100 parts by mass of the base polyolefin resin in the presence of a radical initiator. Can be manufactured with. The reaction temperature for graft modification is preferably 50 to 250 ° C, more preferably 60 to 200 ° C. The reaction time is appropriately set according to the production method. For example, in the case of melt graft polymerization by a twin-screw extruder, it is preferably within the residence time of the extruder, specifically 2 to 30 minutes, and 5 to 10 minutes. Minutes are more preferred. The graft modification can be carried out under either normal pressure or pressurized conditions.

Examples of the radical initiator used for graft modification include organic peroxides such as alkyl peroxide, aryl peroxide, acyl peroxide, ketone peroxide, peroxyketal, peroxycarbonate, peroxyester, and hydroperoxide. Be done.

These organic peroxides can be appropriately selected and used depending on the above-mentioned reaction temperature and reaction time conditions. For example, in the case of melt graft polymerization by a twin-screw extruder, alkyl peroxide, peroxyketal, and peroxyester are preferable, and specifically, di-t-butyl peroxide and 2,5-dimethyl-2,5-di are used. -T-Butylperoxy-hexin-3, dicumyl peroxide and the like are preferable.

As the modified polyolefin resin (a), a polyolefin resin modified with maleic anhydride is preferable, and for example, "Admer" manufactured by Mitsui Chemicals, Inc., "Modic" manufactured by Mitsubishi Chemical Corporation, and the like are suitable. Since such a modified polyolefin resin (a) component has excellent reactivity with various metals and polymers having various functional groups, it is possible to impart adhesion to the adhesive resin layer 15 by utilizing the reactivity. , Electrolyte resistance can be improved.

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

The adhesive resin composition is generated when the modified polyolefin resin (a) component, which is the main component of the adhesive resin layer 15, is laminated by containing the macrophase-separated thermoplastic elastomer (b) component. The residual stress can be released, and the adhesive resin layer 15 can be provided with viscoelastic adhesiveness. Therefore, the adhesiveness of the adhesive resin layer 15 is further improved, and the exterior material 10 having more excellent electrolytic solution resistance can be obtained.

The macrophase-separated thermoplastic elastomer (b) exists in a sea-island shape on the modified polyolefin resin (a), but when the dispersed phase size is 200 nm or less, it is difficult to impart improvement in viscoelastic adhesiveness. 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 with each other, so that the laminating suitability (workability) is significantly reduced. , The physical strength of the adhesive resin layer 15 tends to decrease. From the above, the dispersed phase size is preferably 500 nm to 10 μm.

As such a macrophase-separated thermoplastic elastomer (b), for example, ethylene and / or propylene is selected from 1-butene, 1-pentene, 1-hexene, 1-octene, and 4-methyl-1-pentene. Examples thereof include polyolefin-based thermoplastic elastomers obtained by copolymerizing α-olefins.

As the macrophase-separated thermoplastic elastomer (b) component, a commercially available product can be used, for example, "Toughmer" manufactured by Mitsui Chemicals, "Zeras" manufactured by Mitsubishi Chemical Corporation, and "Cataloy" manufactured by Montel. ] Etc. are suitable.

In the adhesive resin layer 15, the content of the macrophase-separated thermoplastic elastomer (b) component with respect to the modified polyolefin resin (a) component in the adhesive resin composition is based on 100 parts by mass of the modified polyolefin resin (a) component. It is preferably 1 to 40 parts by mass, and more preferably 5 to 30 parts by mass. Here, if the content of the macrophase-separated thermoplastic elastomer (b) component is less than 1 part by mass, improvement in the adhesion of the adhesive resin layer cannot 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. In addition, the workability tends to be significantly reduced. Further, since the macrophase-separated thermoplastic elastomer (b) component is not a resin exhibiting adhesiveness, the adhesiveness of the adhesive resin layer 15 to other layers such as the sealant layer 16 and the corrosion prevention treatment layer 14 tends to decrease. ..

(Polypropylene having an atactic structure or a propylene-α-olefin copolymer having an atactic structure (c))
The adhesive resin layer 15 preferably contains polypropylene having an atactic structure or a propylene-α-olefin copolymer having an atactic structure (hereinafter, simply referred to as “component (c)”) as an additive component. Here, the component (c) is a completely amorphous resin component.

Hereinafter, the effect of adding the additive component (c) to the adhesive resin composition as the main component in the adhesive resin layer 15 will be described.

The component (c) is compatible with the modified polyolefin resin (a) component in the adhesive resin composition when the adhesive resin layer 15 is in a molten state, but is discharged to the outside of the crystal during crystallization with cooling. , Uniformly dispersed around the spherulite. As a result, 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 adhesive resin layer 15, the concentration of the modified polyolefin resin (a) component is diluted by the component (c) and crystal growth is suppressed, so that the adhesive component of the base resin is suppressed. (That is, the crystal size (spherulite size) of the modified polyolefin resin (a) component) can be reduced. Further, the component (c) discharged to the outside of the crystal is uniformly dispersed around the microspherulite of the modified polyolefin resin (a) component. In addition, the whitening phenomenon can be suppressed by the effect of the component (c) as described above.

By the way, it has been conventionally known that a "whitening phenomenon" occurs when an exterior material is cold-molded. Here, the mechanism of the whitening phenomenon will be described by taking as an example the adhesive resin layer 15 in which the modified polyolefin resin (a) is mixed with the macrophase-separated thermoplastic elastomer (b).
(1) The modified polyolefin resin (a) in the adhesive resin layer 15 crystallizes by the heat treatment at the time of thermal lamination.
(2) Since the modified polyolefin resin (a) and the macrophase-separated thermoplastic elastomer (b) are incompatible, distortion occurs at the interface between the modified polyolefin resin (a) and the macrophase-separated thermoplastic elastomer (b) due to the crystallization behavior of (1).
(3) When stress is applied during molding, cracks are generated at the interface between the two, and void-claises are formed.
(4) Light is scattered by void-claise, and a whitening phenomenon occurs due to diffused reflection of optical light.

That is, in order to suppress the whitening phenomenon, "the crystallization of the modified polyolefin resin (a) does not proceed due to the amount of heat during thermal lamination, or even if the crystallization progresses, fine spherulites are formed." It is known that "improving the adhesion between the modified polyolefin resin (a) and 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 which is the main component of the adhesive resin layer 15, the crystal size (spherulite size) of the modified polyolefin resin (a) component is obtained. Can be made smaller, so that flexible and tenacious film properties can be obtained. Further, since the component (c) is uniformly dispersed around the modified polyolefin resin (a), stress can be uniformly relaxed and the generation of void craze can be suppressed. It is considered possible to alleviate the "bleaching phenomenon".

As described above, by adding the component (c) as an additive component to the adhesive resin composition which is the main component of the adhesive resin layer 15, the transparency of the adhesive resin layer 15 is improved and at the time of molding. The whitening phenomenon associated with stress can be alleviated. As a result, the whitening of the molding is also improved, and the insulating property (flexibility) associated with the bending stress of the exterior material 10 can be improved. Further, since the degree of crystallinity of the modified polyolefin resin component (a) in the adhesive resin layer 15 can be maintained and flexibility can be imparted, it is possible to suppress a decrease in the laminating strength of the exterior material 10 when the electrolytic solution is swollen. It becomes.

The lower limit of the ratio of the component (c) in the adhesive resin layer 15 is preferably 2.5% by mass, more preferably 5% by mass or more. On the other hand, the upper limit value is preferably 60% by mass. Here, if the proportion of the component (c) in the adhesive resin layer 15 is less than 2.5% by mass, the effect of adding the component (c) as described above tends not to be sufficiently obtained. be. On the other hand, when it exceeds 60% by mass (that is, when the proportion of the adhesive resin composition is less than 40% by mass), the adhesive resin layer 15 adheres to other layers such as the sealant layer 16 and the corrosion prevention treatment layer 14. It tends to be less sexual.

(Propylene-α-olefin copolymer having an isotactic structure (d))
The adhesive resin layer 15 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 above-mentioned component (c). Is preferable.

By further adding the component (d) as an additive component to the adhesive resin component which is the main component of the adhesive resin layer 15, flexibility for relieving stress can be imparted, so that the strength of the electrolytic solution laminate is lowered. It is possible to improve the heat seal strength (particularly the electrolytic solution resistance) and the degassing seal strength while suppressing the above. Further, by combining the component (c) and the component (d) as the additive component, the whitening phenomenon and the bending insulation resistance can be further improved.

The ratio of the additive component (that is, the total amount of the component (c) and the component (d)) in the adhesive resin layer 15 is preferably 5 to 60% by mass. Here, when the ratio of the additive component in the adhesive resin layer 15 is less than 5% by mass (that is, when the ratio of the adhesive resin composition exceeds 95% by mass), the additive as described above is used. There is a tendency that the effect of the addition is not sufficiently obtained. On the other hand, when it exceeds 60% by mass (that is, when the proportion of the adhesive resin composition is less than 40% by mass), the adhesive resin layer 15 adheres to other layers such as the sealant layer 16 and the corrosion prevention treatment layer 14. It tends to be less sexual.

As a method for analyzing the component (c) which is an additive component in the adhesive resin layer 15, for example, it can be quantified by stereoregularity evaluation by nuclear magnetic resonance spectroscopy (NMR).

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

The adhesive resin layer 15 is composed of an adhesive resin composition (that is, a modified polyolefin resin (a) component and a macrophase-separated thermoplastic elastomer (b) component) and an additive component (that is, a component (c) and a component (d)). ), If necessary, various additives such as flame retardant, slip agent, antiblocking agent, antioxidant, light stabilizer, tackifier and the like may be contained.

The thickness of the adhesive resin layer 15 is not particularly limited, but is preferably the same as or less than that of the sealant layer 16 from the viewpoint of stress relaxation and moisture / electrolytic solution permeation.

<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 contains a single-site catalytic polypropylene resin as a base resin. The sealant layer 16 further contains at least one of a compatible elastomer having compatibility with the single-site catalytic polypropylene resin and an incompatible elastomer having no compatibility with the single-site catalytic polypropylene resin. You may.

(Single-site catalytic polypropylene resin)
The single-site catalytic polypropylene resin is polypropylene polymerized using a single-site catalyst having a uniform active site. Examples of the single-site catalyst include a metallocene catalyst and a transition metal complex having a bis-π-cyclopentadienyl group, and a metallocene catalyst is preferable. Compared with the multisite catalyst, the single-site catalyst can obtain polypropylene having a narrow molecular weight distribution, a small amount of low molecular weight components and low crystal components, and high uniformity. That is, it can be said that the single-site catalytic polypropylene resin is a polypropylene resin that satisfies the range of molecular weight distribution and / or the range of xylene extraction amount described later.

The molecular weight distribution of the single-site catalytic polypropylene resin, that is, the Q value (Mw / Mn), which is the ratio of the weight average molecular weight (Mw) to the number average molecular weight (Mn), is preferably less than 5.5. It is more preferably 5.5 or more and less than 5.5, and further preferably 1.5 or more and less than 4.0. When the Q value is less than 5.5, the insulation after heat sealing, molding and degassing heat sealing can be more sufficiently maintained. In this specification, the weight average molecular weight and the number average molecular weight are measured by gel permeation chromatography (GPC) and converted by a calibration curve using standard polystyrene.

The amount of xylene extracted from the single-site catalytic polypropylene resin at 25 ° C. is preferably less than 1.5% by mass, more preferably less than 1.0% by mass, based on the total amount of the single-site catalytic polypropylene resin. It is preferably less than 0.8% by mass, more preferably less than 0.8% by mass. When the amount of xylene extracted is less than 1.5 mass, the low molecular weight component and the low crystal component are sufficiently small, the effect of the present invention is sufficiently exhibited, and the insulating property after heat sealing, molding and degassing heat sealing is sufficiently exhibited. Can be maintained more adequately. Further, when the amount of xylene extracted is less than 1.5 mass, the electrolytic solution is less likely to swell in the sealant layer 16, and the insulating property and the basic performance of the exterior material (electrolyte solution lamination strength, electrolytic solution heat seal strength, etc.) are deteriorated. It can be better. In this specification, the amount of xylene extracted is a value measured by the following method. First, 2 g of a sample is dissolved in 300 ml of p-xylene (containing 0.5 mg / ml of BHT) at 130 ° C. to prepare a solution, and then left at 25 ° C. for 12 hours. Then, the precipitated polymer is filtered off, p-xylene is evaporated from the filtrate, and the mixture is further dried under reduced pressure at 100 ° C. for 12 hours to recover the room temperature xylene-soluble component. The amount of xylene extracted is determined from the ratio (mass%) of the mass of the recovered component to the mass of the charged sample.

Examples of the single-site catalytic polypropylene resin include propylene homopolymer (homopolypropylene), propylene-ethylene block copolymer (block polypropylene), propylene-ethylene random copolymer (random polypropylene), and α other than ethylene and propylene. -A copolymer of olefin and propylene (propylene-based copolymer) can be mentioned. These can be used alone or in combination of two or more.

Specific examples of the α-olefin as the monomer constituting the propylene-based copolymer include 1-butene, 1-pentene, 3-methyl-1-butene, 1-hexene, 3-methyl-1-pentene, and the like. Contains 4-methyl-1-pentene and the like.

The single-site catalytic polypropylene resin is preferably homopolypropylene or random polypropylene, and more preferably random polypropylene. By using random polypropylene, deep drawing property (moldability) and various seal strengths can be further improved, and molding whitening can be further suppressed. When homopolypropylene or block polypropylene is used, the sealing start temperature tends to be higher and the sealing suitability tends to be lower than when random polypropylene is used. Further, when homopolypropylene is used, the crystallinity is high, so that the deep drawing moldability may be lowered. On the other hand, when block polypropylene is used, molding whitening may easily occur.

The content of the single-site catalytic polypropylene resin in the sealant layer 16 may be 20 to 100% by mass, preferably 40 to 90% by mass, and 60 to 90% based on the total mass of the sealant layer 16. It is more preferably by mass%, and even more preferably 70 to 80% by mass.

The analysis of the single-site catalyst-based polypropylene resin in the sealant layer 16 can be performed by measuring the residue of the single-site catalyst. In this case, after the sealant layer is extracted with a solvent, analysis can be performed by IR (infrared spectroscopy), GC (gas chromatography), GCMS (gas chromatography-mass spectrometry), or the like.

(Compatible elastomer)
The compatible elastomer is an elastomer having compatibility with the single-site catalytic polypropylene resin, and can suppress crystallization of the sealant layer 16 and further give flexibility to the sealant layer 16. By giving the sealant layer 16 flexibility, it is possible to impart functions such as molding whitening resistance and impact resistance to the sealant layer 16. Further, by adding a compatible elastomer to the sealant layer 16, it is possible to improve the sealing characteristics in which the electrolytic solution including the degassing heat seal strength is involved. The term "compatible" with respect to the single-site catalytic polypropylene resin means that the resin is dispersed in the single-site catalytic polypropylene resin with a dispersed phase size of 1 nm or more and less than 500 nm.

As the compatible elastomer, a compatible polyolefin-based elastomer is preferable, and a propylene-α-olefin copolymer is more preferable, because the above-mentioned effects can be more sufficiently obtained. By using the propylene-α-olefin copolymer, it is possible to further improve the sealing properties in which the electrolytic solution is involved, such as the electrolytic solution laminating strength and the degassing heat sealing strength.

The propylene-α-olefin copolymer is a compound obtained by copolymerizing propylene with an α-olefin selected from 1-butene, 1-pentene, 1-hexene, 1-octene and 4-methyl-1-pentene. Can be used. Among these, it is particularly preferable to use a propylene-1-butene random copolymer obtained by copolymerizing 1-butene from the viewpoint of improving sealing properties and compatibility.

As the compatible elastomer, either a multisite catalyst (Ziegler-Natta catalyst, etc.) or a single-site catalyst (metallocene catalyst, etc.) can be used, but the molecular weight distribution is narrow and the low molecular weight component is present. It is more preferable to use a compatible elastomer (single-site catalyst-based compatible elastomer) obtained by using a single-site catalyst because the amount is small. By using a single-site catalytic compatible compatible elastomer, it is possible to suppress a decrease in insulating property after heat sealing, molding and degassing heat sealing.

The molecular weight distribution of the compatible elastomer, that is, the Q value (Mw / Mn), which is the ratio of the weight average molecular weight (Mw) to the number average molecular weight (Mn), is preferably less than 5.5, preferably 1.5 or more. It is more preferably less than 5.5, and even more preferably 1.5 or more and less than 4.0. When the Q value is less than 5.5, deterioration of the insulating property after heat sealing, molding and degassing heat sealing can be more sufficiently suppressed.

As the compatible elastomer, one type can be used alone or two or more types can be used in combination.

In the sealant layer 16, the content of the compatible elastomer may be 0 to 40% by mass, preferably 5 to 30% by mass, and 5 to 20% by mass, based on the total mass of the sealant layer 16. Is more preferable, and 10 to 15% by mass is further preferable. When this content is 5% by mass or more, the effect of improving molding whitening resistance, impact resistance and sealing characteristics can be sufficiently obtained. On the other hand, when this content is 40% by mass or less, it is possible to suppress a decrease in the heat resistance of the sealant layer 16 and to suppress the occurrence of over-adhesion during heat sealing.

(Incompatible elastomer)
The incompatible elastomer is an elastomer that is not compatible with the single-site catalytic polypropylene resin, and can impart impact resistance and cold resistance to the sealant layer 16. Further, by adding an incompatible elastomer to the sealant layer 16, it is possible to improve the sealing characteristics in which the electrolytic solution including the degassing heat seal strength is involved. In addition, having no compatibility with the single-site catalytic polypropylene resin (incompatible) means that the dispersed phase size is 500 nm or more and less than 20 μm in the single-site catalytic polypropylene resin.

As the incompatible elastomer, an incompatible polyolefin-based elastomer is preferable, and an ethylene-α-olefin copolymer is more preferable, because the above-mentioned effects can be more sufficiently obtained. By using the ethylene-α-olefin copolymer, it is possible to further improve the sealing properties in which the electrolytic solution is involved, such as the electrolytic solution laminating strength and the degassing heat sealing strength.

The ethylene-α-olefin copolymer is a compound obtained by copolymerizing ethylene with an α-olefin selected from 1-butene, 1-pentene, 1-hexene, 1-octene and 4-methyl-1-pentene. Can be used. Among these, it is particularly preferable to use an ethylene-1-butene random copolymer obtained by copolymerizing 1-butene from the viewpoint of improving the sealing characteristics.

As the incompatible elastomer, either a multisite catalyst (Ziegler-Natta catalyst, etc.) or a single-site catalyst (metallocene catalyst, etc.) can be used, but the molecular weight distribution is narrow and the low molecular weight component is used. It is more preferable to use an incompatible elastomer (single-site catalyst-based incompatible elastomer) obtained by using a single-site catalyst. By using a single-site catalytic incompatible elastomer, it is possible to suppress deterioration of the insulating property after heat sealing, molding and degassing heat sealing.

The molecular weight distribution of the incompatible elastomer, that is, the Q value (Mw / Mn), which is the ratio of the weight average molecular weight (Mw) to the number average molecular weight (Mn), is preferably less than 5.5, preferably 1.5. It is more preferably 5 or more and less than 5.5, and further preferably 1.5 or more and less than 4.0. When the Q value is less than 5.5, deterioration of the insulating property after heat sealing, molding and degassing heat sealing can be more sufficiently suppressed.

As the incompatible elastomer, one type can be used alone or two or more types can be used in combination.

The content of the incompatible elastomer in the sealant layer 16 may be 0 to 40% by mass, preferably 5 to 30% by mass, and 5 to 20% by mass, based on the total mass of the sealant layer 16. It is more preferably%, and further preferably 10 to 15% by mass. When this content is 5% by mass or more, the effect of improving impact resistance, cold resistance and sealing characteristics in which the electrolytic solution is involved can be sufficiently obtained. On the other hand, when this content is 40% by mass or less, it is possible to suppress a decrease in the heat resistance of the sealant layer 16 and to suppress the occurrence of over-adhesion during heat sealing.

The sealant layer 16 may contain only one of the above-mentioned two types of elastomers, which are compatible and incompatible, but containing both of them provides molding whitening resistance and sealing properties in which the electrolytic solution is involved. It is preferable because it can be improved in a well-balanced manner. In particular, the single-site catalytic polypropylene resin, the propylene-1-butene random copolymer which is a compatible elastomer, and the ethylene-1-buten random copolymer which is an incompatible elastomer have good affinity with each other. By using these in combination, it is possible to improve the molding whitening resistance and the sealing characteristics in which the electrolytic solution is involved in a more balanced manner.

(Additional ingredients)
The sealant layer 16 may further contain components other than the above-mentioned single-site catalytic polypropylene resin, compatible elastomer and incompatible elastomer. As other components, for example, another resin such as LDPE (low density polyethylene) may be added in order to improve the takeability and processability. Further, a polyolefin resin other than the single-site catalytic polypropylene resin (for example, a multi-site catalytic polypropylene resin, a polyethylene resin not limited to the LDPE, etc.) may be added. The content of the other resin component 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 the resin include slip agents, anti-blocking agents, antioxidants, light stabilizers, flame retardants and the like. The content of the 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 1-butene in the sealant layer 16 can be confirmed by attribution by FT-IR (Fourier transform infrared spectrophotometer). The content of 1-butene is determined by the permeability or absorbance of the characteristic absorption band of the single-site catalytic polypropylene resin and the elastomer using a resin composition containing a known amount of an elastomer containing 1-butene. It can be confirmed by creating a calibration curve. Furthermore, the 1-butene content of each of the compatible elastomer and the incompatible elastomer was also imaged in the characteristic absorption band of FT-IR, and 1-butene was subjected to microscopic FT-IR (permeation method). It can be confirmed by mapping in the absorption band of the cause. In addition to FT-IR, it is also possible to confirm the presence and content of 1-butene by dissolving the sealant layer 16 in a solvent and measuring it by NMR.

The thickness of the sealant layer 16 is not particularly limited, but is preferably in the range of, for example, 5 to 100 μm, and more preferably in the range of 10 to 60 μm. Further, the thickness of the sealant layer 16 may be 30 μm or less from the viewpoint of thinning. Further, the total thickness of the sealant layer 16 and the adhesive resin layer 15 (that is, the total thickness on the inner layer side of the metal foil layer 13 provided with the corrosion prevention treatment layer 14) may be 35 μm or less. Even with such a thin film structure, the exterior material for a power storage device of the present embodiment can suppress a decrease in insulating property after heat sealing, molding, and degassing heat sealing.

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

For example, FIG. 1 shows a case where the corrosion prevention treatment layer 14 is formed on the surface of the metal foil layer 13 on the adhesive resin layer 15 side, but the corrosion prevention treatment layer 14 is the first of the metal foil layers 13. It may be formed on the surface on the adhesive layer 12 side, or may be formed on both sides of the metal foil layer 13. When the corrosion prevention treatment layer 14 is formed on both sides 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 adhesive resin layer 15 side may be the same or different.

Further, FIG. 1 shows a case where the metal foil layer 13 and the sealant layer 16 are laminated by using the adhesive resin layer 15, but the adhesive is used as in the exterior material 20 for the power storage device shown in FIG. The metal foil layer 13 and the sealant layer 16 may be laminated by using the layer 17 (sometimes referred to as the second adhesive layer 17). Hereinafter, the second adhesive layer 17 will be described.

<Second adhesive layer 17>
The second adhesive layer 17 is a layer for adhering 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 adhering 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 above-mentioned cationic polymer and anionic polymer, the second adhesive layer 17 is included in the corrosion prevention treatment layer 14. It is preferable that the layer contains a compound having reactivity with the above polymer (hereinafter, also referred to as “reactive compound”).

For example, if the corrosion protection layer 14 contains a cationic polymer, the second adhesive layer 17 contains a compound that is reactive with the cationic polymer. When the corrosion protection treatment layer 14 contains an anionic polymer, the second adhesive layer 17 contains a compound that is reactive with the anionic polymer. 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 have to contain the above two kinds of compounds, and may contain a compound having reactivity with both a cationic polymer and an anionic polymer. Here, "reactive" means forming a covalent bond with a cationic polymer or an anionic polymer. Further, the second adhesive layer 17 may further contain an acid-modified polyolefin resin.

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

Examples of these polyfunctional isocyanate compounds, glycidyl compounds, compounds having a carboxy group, and compounds having an oxazoline group include polyfunctional isocyanate compounds, glycidyl compounds, and carboxy groups exemplified above as cross-linking agents for forming a cationic polymer into a cross-linked structure. Examples thereof include a compound having an oxazoline group and a compound having an oxazoline group. Among these, a polyfunctional isocyanate compound is preferable because it has high reactivity with a cationic polymer and easily forms a crosslinked structure.

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

When the second adhesive layer 17 contains an acid-modified polyolefin resin, it is preferable that the reactive compound is also reactive with the acidic group in the acid-modified polyolefin resin (that is, forms a covalent bond with the acidic group). As a result, the adhesiveness with the corrosion prevention treatment layer 14 is further enhanced. In addition, the acid-modified polyolefin resin has a crosslinked structure, and the solvent resistance of the exterior material 20 is further improved.

The content of the reactive compound is preferably equal to 10 times the equivalent amount of the acidic group in the acid-modified polyolefin resin. When the amount is equal to or more than the equal amount, the reactive compound sufficiently reacts with the acidic group in the acid-modified polyolefin resin. On the other hand, if the amount exceeds 10 times the equivalent amount, the cross-linking reaction with the acid-modified polyolefin resin has reached sufficient saturation, so that unreacted substances are present and there is a concern that 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.

The acid-modified polyolefin resin is one in which an acidic group is introduced into the polyolefin resin. Examples of the acidic group include a carboxy group and a sulfonic acid group, and a carboxy group is particularly preferable. As the acid-modified polyolefin resin, for example, the same ones as those exemplified as the modified polyolefin resin (a) used for the adhesive resin layer 15 can be used.

Various additives such as flame retardants, slip agents, anti-blocking agents, antioxidants, light stabilizers, and tackifiers may be blended in the second adhesive layer 17.

The second adhesive layer 17 is, for example, an acid-modified polyolefin, a polyfunctional isocyanate compound, or a glycidyl compound from the viewpoint of suppressing a decrease in laminate strength when an electrolytic solution is involved and further suppressing a decrease in insulating property. , A compound having a carboxy group, a compound having an oxazoline group, and at least one curing agent selected from the group consisting of a carbodiimide compound. Examples of the carbodiimide compound include N, N'-di-o-toluyl carbodiimide, 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-toluyl carbodiimide and the like can be mentioned.

Further, as the adhesive forming the second adhesive layer 17, for example, a polyurethane-based adhesive in which a polyester polyol composed of a hydrogenated dimer fatty acid and a diol and a polyisocyanate is mixed 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, processability, and the like.

The configuration of the power storage device exterior material 20 other than the second adhesive layer 17 is the same as that of the power storage device exterior material 10. The thickness of the sealant layer 16 in the exterior material 20 for the power storage device is adjusted according to the thickness of the second adhesive layer 17. The thickness of the sealant layer 16 in the exterior material 20 for a power storage device is not particularly limited, but is preferably in the range of, for example, 5 to 100 μm, and more preferably in the range of 10 to 80 μm. Further, the thickness of the sealant layer 16 may be 30 μm or less from the viewpoint of thinning. Further, even if the total thickness of the sealant layer 16 and the second adhesive layer 17 (that is, the total thickness on the inner layer side of the metal foil layer 13 provided with the corrosion prevention treatment layer 14) is 35 μm or less. good. Even with such a thin film structure, the exterior material for a power storage device of the present embodiment can suppress a decrease in insulating property after heat sealing, molding, and degassing heat sealing.

Although FIGS. 1 and 2 show a case where the sealant layer 16 is a single layer, the sealant layer 16 may be a multi-layer. When the sealant layer 16 is multi-layered, at least one of the plurality of layers may be a layer containing a single-site catalytic polypropylene resin.

Further, in FIGS. 1 and 2, the case where the base material layer 11 and the metal foil layer 13 are adhered to each other via the first adhesive layer 12 is shown, but the case is not mediated by the first adhesive layer 12. In addition, the base material layer 11 may be directly formed on the metal foil layer 13 by the coating method. In the present specification, the base material layer directly formed on the metal foil layer 13 by the coating method as described above is referred to as a coating layer. The corrosion prevention treatment layer 14 may be formed on the surface of the metal foil layer 13 on the coating layer side. Hereinafter, the coating layer will be described.

<Coating layer>
The coating layer imparts heat resistance in the sealing process when manufacturing the power storage device, and plays a role of suppressing the occurrence of pinholes that may occur during processing and distribution.

The coating layer is made of resin, and is directly formed on one surface of the metal foil layer 13 without using an adhesive or the like. Such a coating layer can be formed by applying or coating a resin material to be a coating layer on the metal foil layer 13.

As the resin material for forming the coating layer, polyester, fluororesin, acrylic resin and the like can be used, and urethane acrylate is particularly preferable. This is because the coating film made of urethane acrylate has suitable ductility. As the coating liquid containing these resin materials, a two-component curing type coating liquid may be used.

The thickness of the coating layer is preferably 3 μm to 30 μm, more preferably 5 μm to 20 μm. Since the coating layer is formed directly on the metal foil layer 13, it is easy to make the coating layer thinner than the conventional exterior material by setting the thickness of the coating layer to 20 μm or less.

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

The method for producing 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 laminating the base material layer 11 and the metal foil layer 13, and the adhesive resin layer 15 and the adhesive resin layer 15. It is roughly configured including a step of further laminating the sealant layer 16 to prepare a laminated body and, if necessary, a step of heat-treating the obtained laminated body.

(Laminating 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. Examples of the method include a method of subjecting the metal foil layer 13 to a degreasing treatment, a hydrothermal transformation treatment, an anodization treatment, a chemical conversion treatment, and a coating agent having anticorrosion performance. Be done.

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. After forming the first layer, the coating liquid (coating agent) constituting the corrosion prevention treatment layer on the upper layer side may be applied to the first layer and baked to form the second layer. Further, the second layer can also be formed in the step of laminating the adhesive resin layer 15 and the sealant layer 16 described later.

Select the spray method or dipping method for degreasing treatment, the dipping method for hydrothermal transformation treatment and anodizing treatment, and the dipping method, spray method, coating method, etc. for chemical conversion treatment according to the type of chemical conversion treatment. You can do it.

As a coating method for a coating agent having corrosion prevention performance, various methods such as gravure coating, reverse coating, roll coating, and bar coating can be used.

As described above, various treatments may be performed on either the double-sided surface or the single-sided surface of the metal foil, but in the case of the single-sided treatment, the treated surface is preferably applied to the side on which the adhesive resin layer 15 is laminated. If required, the surface of the base material layer 11 may also be subjected to the above treatment.

The amount of the coating agent applied to form 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 .

When drying cure is required, it can be performed in the range of 60 to 300 ° C. as the base material temperature depending on the drying conditions of the corrosion prevention treatment layer 14 to be used.

(A process of bonding the base material layer 11 and the 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 material layer 11 via the first adhesive layer 12. As a method of bonding, methods such as dry lamination, non-solvent lamination, and wet lamination are used, and both are bonded with the material constituting the first adhesive layer 12 described above. The first adhesive layer 12 is provided in a dry coating amount in the range of 1 to 10 g / m ² , more preferably in the range of 3 to 7 g / m ² .

(Laminating step of adhesive resin layer 15 and sealant layer 16)
This step is a step of forming the adhesive resin layer 15 and the sealant layer 16 on the corrosion prevention treatment layer 14 formed in the previous step. Examples of the method include a method of sand lamination the adhesive resin layer 15 together with the sealant layer 16 using an extrusion laminating machine. Further, the adhesive resin layer 15 and the sealant layer 16 can be laminated by a tandem laminating method or a coextrusion method. Alternatively, a sealant single film may be formed in advance as a cast film using a resin composition for forming a sealant layer, and the film may be laminated together with an adhesive resin by sand lamination.

By this step, as shown in FIG. 1, each layer is laminated in the order of base material layer 11 / first adhesive layer 12 / metal foil layer 13 / corrosion prevention treatment layer 14 / adhesive resin layer 15 / sealant layer 16. The finished laminate is obtained.

The adhesive resin layer 15 may be directly laminated by an extrusion laminating machine using a dry-blended material so as to have the above-mentioned material composition, or may be extruded in advance by a single-screw extruder or a twin-screw extruder. The granulated product after being melt-blended using a melt-kneading device such as a machine or a brabender mixer may be used for laminating by an extrusion laminating machine.

Further, when forming the multi-layer corrosion prevention treatment layer 14, if the extrusion laminating machine is provided with a unit capable of coating the anchor coat layer, the second layer of the corrosion prevention treatment layer 14 is formed by the unit. It may be coated.

(Heat treatment process)
This step is a step of heat-treating the laminated body. By heat-treating the laminate, the adhesion between the metal foil layer 13 / corrosion prevention treatment layer 14 / adhesive resin layer 15 / sealant layer 16 is improved, and better electrolyte resistance and acidity resistance are imparted. can do. The temperature of the heat treatment depends on the type of material constituting the adhesive resin layer 15 and the sealant layer 16, but as a guide, the maximum temperature reached by the laminate is higher than the melting point of the adhesive resin layer 15 or the sealant layer 16. Is also preferably heat-treated so as to be 20 to 100 ° C. higher, and more preferably 20 to 60 ° C. higher than the melting point of the adhesive resin layer 15 or the sealant layer 16. If the maximum temperature reached of the laminate exceeds this range, for example, thermal expansion of the metal foil and thermal shrinkage of the base material layer after bonding may occur, which may reduce workability and characteristics. Therefore, the heat treatment time depends on the treatment temperature, but it is desirable to perform the heat treatment in a short time (for example, less than 30 seconds).

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

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

The method for producing 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 laminating the base material layer 11 and the metal foil layer 13, and a second adhesive layer. It is roughly configured including a step of further laminating the sealant layer 16 via 17 to prepare a laminated body and, if necessary, a step of aging the obtained laminated body. The steps up to the step of bonding the base material layer 11 and the metal foil layer 13 can be performed in the same manner as the above-described method for manufacturing the exterior material 10.

(Laminating step of the second adhesive layer 17 and the sealant layer 16)
This step is a step of adhering the sealant layer 16 to the corrosion prevention treatment layer 14 side of the metal foil layer 13 via the second adhesive layer 17. Examples of the bonding method include wet process and dry lamination.

In the case of the wet process, a solution or dispersion of the adhesive constituting the second adhesive layer 17 is applied onto the corrosion prevention treatment layer 14 to a predetermined temperature (when the adhesive contains an acid-modified polyolefin resin). The solvent is blown off at a temperature equal to or higher than the melting point of the resin, and a dry film is formed, or a baking process is performed after the dry film formation, if necessary. After that, the sealant layer 16 is laminated to manufacture the exterior material 20. Examples of the coating method include various coating methods exemplified above.

In the case of dry lamination, a method of forming a sealant single film as a cast film in advance using a resin composition for forming a sealant layer and laminating this film by a dry laminating method using an adhesive can be mentioned. ..

(Aging process)
This step is a step of aging (curing) the laminated body. By aging the laminate, adhesion between the metal foil layer 13, the corrosion prevention treatment layer 14, the second adhesive layer 17, and the sealant layer 16 can be promoted. The aging treatment can be performed in the range of room temperature to 100 ° C. The aging time is, for example, 1 to 10 days. Further, in order to further promote the adhesion between the second adhesive layer 17 and the sealant layer 16, the 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, but are not limited to, oven heating, sandwiching between heated rolls (heat laminating), and winding around a heated roll.

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

Although the preferred embodiment of the exterior material for a power storage device and the method for producing the same of the present invention has been described in detail above, the present invention is not limited to such a specific embodiment and is described within the scope of claims. Within the scope of the gist of the present invention, various modifications and changes are possible. When manufacturing an exterior material for a power storage device having a coating layer instead of the base material layer 11 and the first adhesive layer 12, the resin material to be the coating layer is placed on the metal foil layer 13 as described above. A coating layer can be formed by coating or coating.

The exterior material for a power storage device of the present invention is suitable as an exterior material for a power storage device such as a secondary battery such as a lithium ion battery, a nickel hydrogen battery, and a lead storage battery, and an electrochemical capacitor such as an electric double layer capacitor. Can be used. Above all, the exterior material for a power storage device of the present invention is suitable as an exterior material for a lithium ion battery.

Hereinafter, the present invention will be described in more detail based on Examples, but the present invention is not limited to the following Examples.

[Material used]
The 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 an adduct-based curing agent for tolylene diisocyanate was mixed 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): Distilled water was used as a solvent, and "sodium polyphosphate stabilized cerium oxide sol" adjusted to a solid content concentration of 10% by mass 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 Nitto Boseki)" adjusted to a solid content concentration of 5% by mass using distilled water as a solvent, and "polyglycerol polyglycidyl ether (manufactured by Nagase ChemteX)". A composition consisting of 10% by mass was used.
(CL-3): Chromium fluoride (CrF ₃ ) was finally added to a water-soluble phenol resin (manufactured by Sumitomo Bakelite Co., Ltd.) adjusted to a solid content concentration of 1% by mass using a phosphoric acid aqueous solution having a solid content concentration of 1% by mass as a solvent. A chemical chemical treatment agent whose concentration was adjusted so that the amount of Cr present in the dry film was 10 mg / m ² was used.

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

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

<Adhesive resin layer>
(Resin A): A mixture of the following materials in a mass ratio of (AR-1): (AR-2) = 3: 1 (mass ratio).
(Resin B): The resin composition of (AR-1).

(AR-1): An acid-modified polypropylene resin composition based on random polypropylene (PP) containing ethylene-propylene rubber as an incompatible rubber (Admer, manufactured by Mitsui Chemicals, Inc.).
(AR-2): A propylene-α-olefin copolymer having an atactic structure (manufactured by Sumitomo Chemical Co., Ltd., “Tough Serene H”).

<Sealant layer>
(Base resin): Homopolypropylene or random polypropylene (propylene-ethylene random copolymer) polymerized using the single-site catalyst (metallocene catalyst) or multi-site catalyst (Ziegler-Natta catalyst) shown in Table 1.
(Compatible elastomer): A propylene-1-butene random copolymer polymerized using a single-site catalyst (metallocene catalyst) or a multi-site catalyst (Ziegler-Natta catalyst) shown in Table 1.
(Incompatible elastomer): An ethylene-1-butene random copolymer polymerized using a single-site catalyst (metallocene catalyst) or a multi-site catalyst (Ziegler-Natta catalyst) shown in Table 1.

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

Next, the first corrosion prevention treatment layer side of the metal foil layer provided with the first and second corrosion prevention treatment layers is based by a dry laminating method using a polyurethane adhesive (first adhesive layer). It was attached to the material layer. This is set in the unwinding part of the extrusion laminating machine and co-extruded onto the second corrosion prevention treatment layer at 270 ° C. and 100 m / min processing conditions to obtain an adhesive resin layer (thickness 10 μm) and a sealant layer (thickness 10 μm). (Thickness 20 μm) was laminated in this order. The adhesive resin layer and the sealant layer were prepared in advance using a twin-screw extruder to prepare compounds of various materials, and were used for the extrusion laminating after undergoing a water cooling and pelletizing process. Resin A was used to form the adhesive resin layer. For the formation of the sealant layer, a resin composition obtained by mixing a single-site catalytic homopolypropylene as a base resin, a single-site catalytic compatible compatible elastomer, and a single-site catalytic incompatible elastomer was used. The content of each of the above components in the sealant layer is as shown in Table 1.

The laminate thus obtained is heat-treated so that the maximum temperature of the laminate reaches 190 ° C., and the exterior material (base material layer / first adhesive layer / first) of Example 1 is subjected to heat treatment. One corrosion prevention treatment layer / metal foil layer / second corrosion prevention treatment layer / adhesive resin layer / sealant layer laminate) was manufactured.

[Example 2]
The exterior material of Example 2 was produced in the same manner as in Example 1 except that single-site catalytic random polypropylene was used as the base resin of the sealant layer.

[Examples 3 to 5]
The exterior materials of Examples 3 to 5 were produced in the same manner as in Example 2 except that the content of each component in the sealant layer was changed as shown in Table 1.

[Examples 6 to 7]
The exterior materials of Examples 6 to 7 were produced in the same manner as in Example 2 except that the single-site catalytic random polypropylene having the xylene extraction amount and the molecular weight distribution shown in Table 1 was used.

[Examples 8 to 15]
Example 8 in the same manner as in Example 2 except that the presence or absence of addition of compatible elastomers and incompatible elastomers and / or the type of catalyst used in synthesizing them was changed as shown in Table 1. To 15 exterior materials were manufactured.

[Example 16]
The exterior material of Example 16 was produced in the same manner as in Example 2 except that the resin B was used for forming the adhesive resin layer.

[Example 17]
First, the first and second corrosion prevention treatment layers were provided on the metal foil layer by the following procedure. That is, (CL-3) was applied to both surfaces of the metal foil layer by a microgravure coat so that the dry application amount was 30 mg / m ² , and the drying unit was baked at 200 ° C. Next, (CL-2) is coated on the obtained layer with a microgravure coat so that the dry coating amount is 20 mg / m ² , and the obtained layer is composed of (CL-3) and (CL-2). The composite layer was formed as the first and second corrosion protection treatment layers. This composite layer exhibits corrosion prevention performance by combining two types of (CL-3) and (CL-2). The exterior material of Example 17 was produced in the same manner as in Example 2 except that the metal foil layers provided with the first and second corrosion prevention treatment layers were used in this way.

[Example 18]
First, the first and second corrosion prevention treatment layers were provided on the metal foil layer by the following procedure. That is, (CL-3) is applied to both surfaces of the metal foil layer by a microgravure coat so that the dry coating amount is 30 mg / m ² , and the drying unit is baked at 200 ° C. The first and second corrosion protection treatment layers were formed. The exterior material of Example 18 was produced in the same manner as in Example 2 except that the metal foil layers provided with the first and second corrosion prevention treatment layers were used in this way.

[Example 19]
The first and second corrosion prevention treatment layers were provided on the metal foil layer in the same manner as in Example 1. The first corrosion prevention treatment layer side of the metal foil layer provided with the first and second corrosion prevention treatment layers is made into a base material layer by a dry laminating method using a polyurethane adhesive (first adhesive layer). I pasted it. Next, the second corrosion prevention treatment layer side of the metal foil layer provided with the first and second corrosion prevention treatment layers is cast in advance by the dry laminating method using the adhesive a (second adhesive layer). It was attached to a sealant layer (thickness 30 μm) formed as a film.

The laminate thus obtained is subjected to an aging treatment at 40 ° C. for 4 days, and the exterior material (base material layer / first adhesive layer / first corrosion prevention treatment layer / metal) of Example 19 is applied. A foil layer / a second anti-corrosion treatment layer / a second adhesive layer / a laminate of a sealant layer) was produced.

[Example 20]
The exterior material of Example 20 was manufactured in the same manner as in Example 19 except that the adhesive used for forming the second adhesive layer was changed to the adhesive b.

[Comparative Example 1]
The exterior material of Comparative Example 1 was produced in the same manner as in Example 8 except that the multisite catalyst-based random polypropylene was used as the base resin of the sealant layer.

[Comparative Example 2]
The exterior material of Comparative Example 2 was produced in the same manner as in Example 2 except that the multisite catalyst-based random polypropylene was used as the base resin of the sealant layer.

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.

(Electrolytic solution laminate strength)
An electrolytic solution prepared by adding LiPF ₆ to a mixed solution of ethylene carbonate / diethyl carbonate / dimethyl carbonate = 1/1/1 (mass ratio) so as to be 1 M is filled in a Teflon (registered trademark) container, and an exterior material is contained therein. A sample cut into 15 mm × 100 mm was placed therein, and the mixture was stored at 85 ° C. for 24 hours after sealing. After that, co-washing is performed, and the lamination strength (T-shaped peeling strength) between the metal foil layer / adhesive resin or between the metal foil layer / second adhesive layer is measured using a testing machine (manufactured by INSTRON). did. The test was carried out according to JIS K6854 at 23 ° C., in a 50% RH atmosphere, and at a peeling speed of 50 mm / min. Based on the results, evaluation was made according to the following criteria.
A: Laminate strength is over 9N / 15mm B: Laminate strength is 7N / 15mm or more, 9N / 15mm or less C: Laminate strength is 5N / 15mm or more, less than 7N / 15mm D: Laminate strength is less than 5N / 15mm

(Electrolytic solution heat seal strength)
A sample obtained by cutting the exterior material into 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) so as to be 1 M to the exterior material which was also heat-sealed on the remaining two sides and formed into a bag shape. After storing the pouch in which 2 ml of the electrolytic solution was injected at 60 ° C. for 24 hours, the first side of the heat seal was cut to a width of 15 mm (see FIG. 3), and the sealing strength (T-shaped peeling strength) was measured by a testing machine (INSTRON). It was measured using (manufactured by the company). The test was carried out according to JIS K6854 at 23 ° C., in a 50% RH atmosphere, and at a peeling speed of 50 mm / min. Based on the results, evaluation was made according to the following criteria.
A: Seal strength 90N / 15mm or more, burst width more than 5mm B: Seal strength 80N / 15mm or more, burst width more than 5mm C: Seal strength 40N / 15mm or more, less than 80N / 15mm D: Seal strength 40N / Less than 15mm

(Degassing heat seal strength (Degas heat seal strength))
A sample obtained by cutting the exterior material into 75 mm × 150 mm was folded in half to 37.5 mm × 150 mm (see FIG. 4 (a)), and then one of the 150 mm side and the 37.5 mm side was heat-sealed to make a bag. Then, in the pouch, 5 ml of an electrolytic solution prepared by adding LiPF ₆ to a mixed solution of ethylene carbonate / diethyl carbonate / dimethyl carbonate = 1/1/1 (mass ratio) so as to be 1 M was injected, and the area was 37.5 mm. The other side of the pouch was heat-sealed to obtain a pouch sealed by the sealing portion S1. Next, after storing this pouch at 60 ° C. for 24 hours, the central portion of the pouch was heat-sealed at 190 ° C., 0.3 MPa, 2 sec with the electrolytic solution contained (degassing heat-sealed portion S2, FIG. 4 (b). ). In order to stabilize the seal part, after storing at room temperature for 24 hours, the area including the degassing heat seal part S2 is cut to a width of 15 mm (see FIG. 4C), and the heat seal strength (T-shaped peeling strength). ) Was measured using a testing machine (manufactured by INSTRON). The test was carried out according to JIS K6854 at 23 ° C., in a 50% RH atmosphere, and at a peeling speed of 50 mm / min. Based on the results, evaluation was made according to the following criteria.
A: Seal strength is 70N / 15mm or more B: Seal strength is 40N / 15mm or more and less than 70N / 15mm C: Seal strength is 30N / 15mm or more and less than 40N / 15mm D: Seal strength is less than 30N / 15mm

(Whitening after molding (whitening after molding))
A normal sample of the exterior material and a sample stored at 60 ° C. for 1 week are cut into 120 mm × 200 mm, set in a cold molding die so that the sealant layer is in contact with the convex portion of the molding machine, and the molding speed is 5 mm / A deep drawing of 2.0 mm was performed in sec. After that, whitening of the side of the film holding portion, which is the most severely stretched, was observed. As the mold, a mold having a molding area of 80 mm × 70 mm (square cylinder type) and a punch corner radius (RCP) of 1.0 mm was used. 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 normal sample and sample stored at 60 ° C for 1 week B: No whitening in normal sample, thin whitening in sample stored at 60 ° C for 1 week C: Thin whitening in normal sample, stored at 60 ° C for 1 week Whitening with sample D: Whitening with normal sample

(Heat sealing, molding and degassing Insulation after heat sealing (heat sealing, molding, degas insulation))
A sample 40 obtained by cutting the exterior material into 120 mm × 200 mm is set in a cold molding die so that the sealant layer is in contact with the convex portion of the molding machine, and a deep drawing of 2.0 mm is performed at a molding speed of 15 mm / sec. After forming the deep drawing portion 41, it was folded in half to 120 mm × 100 mm (see FIG. 5 (a)). Next, the top side portion 44 of 100 mm was heat-sealed with the tab 42 and the tab sealant 43 sandwiched between them (see FIG. 5B), and then the side side portion 45 of 120 mm was heat-sealed to form a bag. (See FIG. 5 (c)). Then, in order to bring the electrodes into contact with each other, a part of the outer layer of the sample 40 was scraped to form an exposed portion 46 of the metal foil layer (see FIG. 5D). Next, 5 ml of an electrolytic solution prepared by adding LiPF ₆ to a mixed solution of ethylene carbonate / diethyl carbonate / dimethyl carbonate = 1/1/1 (mass ratio) so as to be 1 M was poured into the pouch, and the lower side portion of 100 mm was injected. 47 was sealed with a heat seal (see FIG. 5 (e)). After that, the pouch was left flat at 60 ° C. for 24 hours, and the portion 48 inside the heat-sealed lower side portion 47 was bitten by the electrolytic solution at 190 ° C. and 0.3 MPa (surface pressure). ), Degassing heat-sealed in 2 sec (see FIG. 5 (f)). Next, the electrodes 49a and 49b are connected to the tab 42 and the exposed portion 46 of the metal foil layer, respectively, and 25 V is applied using a withstand voltage / insulation resistance tester (manufactured by KIKUSUI, “TOS9201”), and the resistance value at that time is applied. Was measured (see FIG. 5 (g)). As the mold, a mold having a molding area of 80 mm × 70 mm (square cylinder type) and a punch corner radius (RCP) of 1.0 mm was used. Based on the results, evaluation was made according to the following criteria.
A: Resistance value exceeds 200MΩ B: Resistance value is 100MΩ or more and 200MΩ or less C: Resistance value is 30MΩ or more and less than 100MΩ D: Resistance value is less than 30MΩ

Further, for the sample whose resistance value is less than 30 MΩ (D evaluation) in the above evaluation result, an additional 25 V is applied between the electrodes 49a and 49b by using a withstand voltage / insulation resistance tester (manufactured by KIKUSUI, “TOS9201”). It was applied for a period of time to identify the location of insulation deterioration. By applying the voltage for a long time, the reaction product of the metal foil layer (aluminum foil) and the electrolytic solution is precipitated from the insulation deteriorated portion, so that the insulation deteriorated portion can be specified.

(Comprehensive quality)
The results of each of the above evaluations are shown in Table 2. In Table 2 below, if each evaluation result does not have a D evaluation, it can be said that the overall quality is excellent.

As is clear from the results shown in Table 2, it was confirmed that the exterior materials of Examples 1 to 20 were excellent in insulating properties after heat sealing, molding and degassing heat sealing. Further, it was confirmed that the exterior materials of Examples 1 to 20 had sufficient performance in electrolytic solution lamination strength, electrolytic solution heat seal strength, degassing heat seal strength, and molding whitening.

On the other hand, it was confirmed that the exterior materials of Comparative Examples 1 and 2 had reduced insulating properties after heat sealing, molding and degassing heat sealing. Further, it was identified that the insulation deteriorated portions of the exterior materials of Comparative Examples 1 and 2 after the heat sealing, molding and degassing heat sealing were the degassing heat sealing portion and the top sealing portion.

10, 20 ... Exterior material for power storage device, 11 ... Base material layer, 12 ... First adhesive layer, 13 ... Metal foil layer, 14 ... Corrosion prevention treatment layer, 15 ... Adhesive resin layer, 16 ... Sealant layer, 17 ... Second adhesive layer, 40 ... Sample, 41 ... Deep drawing part, 42 ... Tab, 43 ... Tab sealant, 44 ... Upper side part, 45 ... Side side part, 46 ... Exposed part of metal foil layer, 47 ... Lower side portion, 48 ... Internal portion from the lower side portion, 49a, 49b ... Electrode, S1 ... Seal portion, S2 ... Degassing heat seal portion.

Claims (8)

Exterior for power storage device having a structure in which at least a base material layer, a metal foil layer provided with a corrosion prevention treatment layer on one or both surfaces, an adhesive layer or an adhesive resin layer, and a sealant layer are laminated in this order. It ’s a material,
The sealant layer contains a single-site catalytic polypropylene resin and contains.
For a power storage device used for a power storage device having an electrolytic solution, the amount of xylene extracted from the single-site catalytic polypropylene resin at 25 ° C. is less than 1.5% by mass based on the total amount of the single-site catalytic polypropylene resin. Exterior material. The exterior material for a power storage device according to claim 1, wherein the single-site catalytic polypropylene resin contains a propylene-ethylene random copolymer. The sealant layer is not compatible with the propylene-α-olefin copolymer, which is a compatible elastomer having compatibility with the single-site catalytic polypropylene resin, and the single-site catalytic polypropylene resin. The exterior material for a power storage device according to claim 1 or 2, further comprising at least one of an ethylene-α olefin copolymer which is an incompatible elastomer. The exterior material for a power storage device according to claim 3, wherein at least one of the propylene-α-olefin copolymer and the ethylene-α-olefin copolymer is a single-site catalytic elastomer. The exterior material for a power storage device according to claim 3 or 4, wherein the ethylene-α-olefin copolymer is a single-site catalytic elastomer. The exterior material for a power storage device according to any one of claims 3 to 5, wherein the propylene-α-olefin copolymer and the ethylene-α-olefin copolymer are single-site catalytic elastomers. The exterior material for a power storage device according to any one of claims 1 to 6, wherein the adhesive resin layer contains an acid-modified polypropylene and an tactical polypropylene or an tactical propylene-α-olefin copolymer. .. 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 6.

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